A few reflections on the trio you are interested in:
Guam: worth a couple of days of diving, but steer clear of MDA and GTDS because they tend to run cattle boats. (There are some great shore dives there, but you really need a local to show you the ropes. If you can find it, Gun Beach is really a very nice shore dive.) Now, back to boat dives. The Blue Hole is not much of a dive, in my opinion; if the DM will let you roam around the top of the hole whilst everyone else scoots through it, you might see more then the rest of the group. That said, if you do macro photography and take your time ascending the Blue Hole, you might just get some fine photos! The harbor wrecks, the Tokai Maru and the Cormoran, are okay dives if the viz is not too bad. However, it is usually fairly poor. Scoot on over to Rock's Reef or Western Shoals and you will likely see one of the prettiest schools of Batfish around. I think there is a "tourist" sub that uses that area and feeds the fish, hence they tend to stick around!
Yap: the diving here is not as good as on Palua, however, what you come for are the Mantas! A warning, though, 75% of the time they either do not show up or the vis is atrocious! I would not spend more than 2-3 days there and pray for mantas. The Manta Ray Bay Hotel is the most convenient place to stay and Bill Munn, the Chef, runs a fantastic restaurant! Be sure to have some of the local, small bananas with breakfast: they are a real treat. But, that said, I will tell you that we ate at the all three of the "Big Three" hotels on Yap and had meals that were superb--I mean SUPERB!
Palua: this is the place to go. Because I have been to all three sites, perhaps, I feel no need to return to the other two. So, if you decide to spend 2 weeks on Palau, you will not be sorry: it is probably the premier dive spot in Micronesia. The Blue Corner is definitely the place to dive, dive, dive! Most DM's will take you there let you hook on with a reef hook and stick around for 5-10 minutes. After you have done that once, I suggest doing the Corner again and just stay there: it simply does not get much better. I am fairly pushy and "insist" on lots of trips to the Corner: going there three times in a week would not be too much! No way!
Big Dropoff and Ngemelis Wall are also absolutely wonderful sites. A drift dive along the Wall will reveal such an abundance of sealife that you will not want to return to the boat! Not to be missed!
Each of the dive shops on Palua has a distinct personality. I am hesitant to recommend one because each one can rub a given diver the wrong way. Sam's has a reputation for haughty DM's (mostly American DM's) that look down their noses at most divers. NECO Marine's DM's tend to be somewhat young and their lack of experience can be a pain. Fish'N'Fins has a its own "problems" according to some folks. So, I would just pick one and be laid back and enjoy the experience.
I guess I have to say the PPR, Palau Pacific Resort, is the place to stay. It may be somewhat pricey, but the accomdations are excellent. Also, if you are an U/W photographer, the photo shop there, Splash, is great! They do E6 processing and usually get your slides back the next day. They used to do color prints (or have them sent out) and that service was great, too. I am not certain that they still do that.
A word about Truk: be sure to get there someday (soon). The facility is deteriorating and I am not certain how long it will last. The latest typhoon did not help in that regard. Every year the resort goes downhill just a little more and I do not see an end in sight for the deterioration. But the diving is pure joy. Of all the night dives in the Western Pacific to do, diving one of the wrecks in the Lagoon at night is my choice! The soft coral is resplendant and the sealife is teeming! You just gotta go to Truk one of these days(Did I mention soon?)! Oh, yes, the Blue Lagoon is the place to stay, in my opinion. The Truk Stop, even at its best, does not compare. However, remember my words of warning: the resort is on the downhill road!
Scorpionfish, Only Its Mother Could Love That Face!
