Galapagos would have to top my list as well. Whale sharks, enough said. On the first trip, we had excellent conditions in the central islands as well. Lousy conditions in the central islands on the second trip, but we did much more whale shark diving because it was a 10-day boat. When you're not seeing whale sharks, all the hammerheads and Galapagos sharks are too shabby either. Not sure if they still mix in land tours under the latest park regs, but that's what made these liveaboards extra special for me.
Cocos. The diving was definitely spectacular and we had a really good group aboard. A former Nekton captain who now works on the Truk Odyssey, one of Sylvia Earle's daughters, a curator of the Maui Ocean Center, harmonicas, guitars, and beer on tap on the sun deck. Good stories, good music, great diving.
Bali-Komodo. This was my first trip to amazing Indonesia, a Komodo liveaboard round trip from Bali. Some sites were disappointing, but most were amazing. Black sand night dive somewhere in the middle of nowhere where cows were walking on the shore. Cannibal Rock again and again (wow!). Komodo dragons. Downside was almost empty boat (8 pax) and my brand new dive lights flooded early in the trip, but it was great overall and land touring on Bali an added bonus (volcano, sea temple, monkey forest, et al.)
Tuamotus. The short-lived Tahiti Aggressor, when it left out of Rangiroa, took us to some amazing sites. Strongest currents I've ever experienced. The most sharks I've ever seen on one dive. Dolphins, mantas. A couple of decent dives off Moorea on the same trip, one where I was in the middle of a local chum fest for blacktips.
Palau. I love Palau, probably my favorite dive destination. Not first on my list because the others had something extra and because my two Palau trips were as much as than play. First time was a "fam" trip with a two-hour seminar each morning and touring of various hotels, dive shops, and liveaboards in the afternoons, diving in the middle, partying at night. Very busy. Short but sweet. Second trip was a photo class (Mike & Mike on the Aggressor, plus Jim Church's ashes) so more seminars. I'd love to make a third trip with no other agenda besides diving. Beautiful rock islands. Jellyfish lake. Chandelier Cave. Mandarinfish Lake. Crazy diving at Peleliu. WWII history. No malaria. I love Palau.
Yap. Spent a week at the Manta Ray Bay resort when they still had waterbeds in the rooms and the restaurant on the top floor. Dove most days with Bill and Patricia. Hot tea and fresh baked banana bread on the SI. Chewing betel nut underwater and spitting through the reg. Topless women. The most exotic place I've ever visited.
Wakatobi. I liked some sites way more than others and wish they didn't adhere to such a strict schedule (damn Swiss!) and wish the A/C was a little better in our bungalow, but otherwise this was the apex of all dive resorts. Incredibly spacious dive boats. Amazing camera service. Actually, all service was amazing there. And the food!
Thailand/Burma. I wish the diving had been better so this trip could have ranked higher. It was my first visit to Thailand and we had excellent diving on the way up to Burma, but the Burma Banks were disappointing - no sharks. And the most depressing dive I've ever done, a post-dynamite night dive: dead or dying fish everywhere. And then the tsunami hit, cutting our trip short and I ended up driving to Bangkok from Phuket, something I'd wish on no one. Still, we survived and have some incredible memories.
Truk. A week on the Odyssey diving tropical wrecks. My longest dive to date (100 min) and at the time my deepest (167'). History in your face, yet surrounded by Indo-Pacific marine life. Kind of grungy on the island, the best reason as any to do a liveaboard instead, and the Odyssey was an excellent platform.
San Benitos Islands. Not even sure if they run this trip anymore since the Guadalupe white shark diving seems to have all the boats chartered full time now, but these are the islands closer to shore than Guadalupe and without the white sharks. Fine with me, I'd rather not "dive" a week in a cage thank you. It was billed as the Channel Islands before civilization and that's what it felt like. Only a tiny lobster village on one island, abandoned for the summer season. Guadalupe fur seals among other pinnipeds barking at us on surface intervals and a really annoying bull sea lion that followed the boat around and would hang around the ladder, making it a bit unnerving to climb out of the water. But amazing diving. Clear water, much warmer than the Channel Islands (around 75 F), but all the usual kelp critters. The first and only guitarfish I've seen in the wild. Fishing on the way down that yielded lots of albacore, yellowtail, and a blue fin that I sampled one night on the grill before the chef turned the rest into sashimi.
Cuba: I wish I could remember more of the diving, but daiquiris and beers were so cheap... Did some rough water diving in Havana Bay, where we were at first turned back because we hadn't brought our passports. Bay of Pigs shore diving was my favorite. Deep wall. Then lobster lunch at a little place with a cenote in the back complete with U.S. unexploded ordinance at 90'. Plenty of memories from that trip, though not as much of the diving.
Bonaire: four trips to date. My favorite Caribbean island, just wish it were easier to get to. J broke her ankle on the last trip so it was less fun and much less diving, but we still managed to have a good time. Met Ned DeLoach at Cactus Blue and Moogie included J and her ankle in a song he sang on his B day.
Cozumel: My lastest go-to place, have had lots of fun trips ranging from large dive shop group, to ferrying over for the day from Cancun/PDC, to a "long weekend" Carnival with the late Bob Ling, to my last two trips I did all by my lonesome and still managed to have fun. Great diving, gets better ever post-Wilma year, and even better now that I found Jeremy and his excellent dive op, Living Underwater.
Local trips: I used to like weekend liveaboards when I used to like cold water diving. Cortez Banks on the Horizon was probably my favorite, especially because I got certified out there, but plenty of great dives at San Clemente, Santa Barbara, and of course Catalina. Farnsworth Banks is very impressive. And I did an oil rig trip once that was mind blowing.
Other notables, good and bad:
Grand Cayman. Lots of good dives there, shore and boat, but I wish the diving were even better. Did a tech class at Cobalt Coast and that was a lot of fun as well as hard work.
Roatan: Resort DM puffed up a puffer, hadn't seen that since the couple of dives I did in Zihuatenejo when I first certified, guess political correctness hadn't hit there yet. Amazing shark dive. They fed Caribbean reef sharks, then let us swim around with them close enough to touch.
Kona: Manta night dive, so amazing that J insisted we do it again the next night.
Maui: I wish Amy still worked at Ed Robinson's. She was my favorite DM before I met Jeremy from Living Underwater in Cozumel. Back wall.
Kauai: Not as impressed with the dives there, except for one we did with Linda from Bubbles Below where she basically covered several turtle-infested sites, knowing the reef like the back of her hand.
Turks & Caicos. Another half-empty liveaboard, but a fun group on the Aggressor and great crew. Diving was very good, lots of sharks. Brand new video lights were dead on arrival so that was a bummer.
La Paz. First dive trip ever besides weekend boats out of SoCal. Stayed far from town, dove with large dive shop group on super slow boats, would take 1.5-3 hours each way to dive sites and the head would usually clog up after lunch. Traveled there after a hurricane had warmed up the water and caused a plankton bloom so viz was far, far from optimal. No hammerheads spotted at El Bajo. Maid would let 1,000,000 flies into our room when she cleaned each day. But we still had fun.
Florida. I really liked Boynton diving. Spiegel Grove was fun. Key Largo reefs? Ugh. I've heard the diving off Key West ain't so good, but I recently stopped there for my first time on a cruise and had a blast.
Belize. A week on the defunct Nekton Pilot. The atolls were beautiful, but the boat barely moved so it seems as if we were doing the same site all day every day. Then again, I found some of the same monotony at Wakatobi. Also did a day of diving off Ambergris Caye while staying there with friends, the rest of the days were blown out. Won't comment on that day (it sucked!) because I've heard it can get better and I don't want to hurt anyone's feelings. Blue Hole is still on my bucket list, but it make take a while to get there.
Cabo Pulmo. Drove a couple of hours to get there only to get on a boat with a trainee DM who didn't know the reef at all. Then, for whatever lame reason, they had us do the same exact site for our second dive. Saw the hairiest girl I've ever seen (said trainee DM) so that at least was cool. Destroyed the rental car on the ride back.
Los Cabos. I liked the diving around El Arco - sort of interesting where the Sea meets the Pacific. The "corridor" diving wasn't as great. We recently did another 3 dives in CSL off a cruise ship and it was still a good time.
Puerto Vallarta. Two dives off a cruise. Kind of a pain since the dive shop was located on a pedestrian only drag so I had to carry two sets of dive gear for four blocks. Then, after renting some 7 mil shorties (cold water!), we had to lug everything to a panga on the beach which took us out to the moored dive boat. Diving was better than I had expected. Not as cold as I had feared and it was so murky that it was practically dark at 30', so dark that all sorts of morays were free swimming everywhere. Lots of nudis too. Really wish I had brought a camera to shoot macro.
Puerto Rico. Tried Fajardo (lousy) and Humacao (a little better) and drove to the other side of the island one day to try Guanica. After a 3 hour drive to get there, we only did one dive because the DM thought it too windy to risk another. Even longer drive back when I tried driving La Ruta Panoramica and we had a blow out. Pulled over on a soft shoulder and the wheel promptly sank into the ground. Started to freak out when the only other soul around was a old woman who, while we were watching, grabbed a chicken and wrung its neck. Started to hear Deliverance banjos playing in my head, but with a hispanic lilt. Fortunately the old lady turned out to be friendly. As soon as she was done killing her chicken, she got some of the menfolk to help us. They managed to get a board under the car and jack it up, even changed the tire for me, and refused my cash offerings. Not at all impressed with the diving, but the island was a fun visit.
Cancun. Tried a couple of dives, not impressed. Almost the same as diving off Ft. Lauderdale, except the water was really cold for some reason (especially odd in September!).
Puerto Morelos. Did a wreck dive that ended up being an exhausting swim back to the line in current, blew off the second dive because I didn't like the DM and wasn't having much fun.