I have done hundreds (or more) dives in Palau, and lived and worked in Palau as a diver for a couple of years. A few thoughts:
If you want to dive the hell out of it, go liveaboard. Lots more diving, and you really can avoid alot of the crowds with early dives, late dives, and dives while the land sharks are off-gassing. ANother factor is that Koror is not the most charming place in the world. In fact, alot of folks are really tunred off by it. Not very idyllic. Having said that, there are a few worthy places. Best bar is certainly Kramers. Great place, with excellent food. Don't underestimate Kramer's food! The bar at Sam's is fine, albeit a bit claustrophobic. I reckon the the Drop Off Bar at Neco Marine across the way makes for a much better dive bar. Try the Rock Island Iced Tea--phew! And the Poke is outstanding, and a silly good deal. Another funky little dive bar option is The Rip Tide, down at the end of the Malakal road. The best Burger is not at Sam's, but out of the Ben Ermi trailer near the ball field. Awesome! The Taj has amazingly good Indian food, and there is also great Thai nearby. The Rock Island Cafe has surprisingly good pizza, and good american-style breakfsts as well. My favorite "budget"/diver hotel is DW's, pretty much right across the street from the Rock Island Cafe. Really good place, with great rates, and in the best area of town (if you are not resorting it at Palau Pacific Resort, which is beautiful, but pricey).
Dive Ops: Sam's get's the most press, and it is a great op. Fish n Fins gets good press as well, and while I tihnk it is a good op, it always seems sort of moody, and the location next to the dump sucks. I think that Neco Marine is the best choice for land ops. By far the best boats (bigger, newer, faster, way more comfy) and facilities. Not even a close call. If you go land based and do not stay at PPR, it may be worth going over for a look and a drink and/or meal, if you can afford it! Nice place. Great for sundowners.
If you want a liveaboard, I would say either Aggressor or the "new" Tropic Dancer. Same folks behind both, but the Dancer is in better shape, having just gone through a serious refit. Either way, ask for Ike--and shout at him: "I like Ike"! He has been boating and diving Palau for over 20 years! Excellent...
Blue Corner ranges from amazing to awesome, depending mainly on current. Dive it multiple times. Best on the incoming, with reef on right, but always good. Also, Blue Holes "outgoing" (reef on left), with a drift all the way to the Corner. New Drop Off is one of my favs, and generally has the best viz. Bi Drop Off is way over-rated, but can do in a pinch when the wind is wrong. Better is Turtle Wall, between Big Drop and New Drop--really, really nice, especially when the Sun is on it. German is great when you get bait balls, Mantas or both, but if it's quiet and the viz is down, not so much. A way underrated dive: Virgin Blue Hole. Love it! a bit deep for a bit, then do reef on right, through the yellow soft coral arch and such. Another way underrated dive: Ngedebus Corner, with reef on right. Awesome in the afternoon Sun! Love it! Need a Peleliu permit, tho. Same with Turtle Cove, and Ngedebus Coral Garden (both worthy). Speaking of Peleliu: Awesome! Peleliu Wall (West Wall) is special. Peleiu Cut is one of the best dives anywhere when the current is ripping and the fish are out! And the Express can be short but amazing. And Barracks/Orange Beach is sweet as well. Ya gotta get to Peleliu! And you can do the Land Tour during a surface interval. Arrange it through Tangee, who started the tour and built the museum, etc. He has become a sort of international legend. Quite a character. Be careful wandering off road alone, as the "growers" might get mad at you. Lotta growers. A classic day: Siaes Tunnel outgoing (reef on right)--awesome; followed by Siaes Corner outgoing (reef on right)--I saw more sharks here one day than I have seen anywhere else in Palau; followed by Ulong Channel incoming. Watch for Dolphins while motoring. Awesome day. And don't forget the Wrecks. Proper WWII wreks. You usually do a wreck dive first, near town, and then off-gas after the dive on your way out to the reefs, and by the time you get to the reefs, you are about ready to dive again. The Iro maru and the Chuyo maru are great. Yowza--I just got back from Palau and I am already itching to go back!
Doug is an amazing cook. Ok, on shore: the best pizza is at rick island cafe, best classy joint is the Taj (Indian food) best burger, fries and onion riings at Bottom time (Sams place, right at the dock) or Kramers. Best beer , Kramers (or so I was told by Scott
