Hi, Hydronium Ion!
To me, the diving on Yap is all about Manta Rays and that is a chancy item. In my experience, the mantas come in mostly when the water is rich in plankton and, hence, the vis is poor. However, there are days when they come to the cleaning station(s) and the vis is great. The best time to go to the cleaning station is at slack tide. If you are there when the mantas show up, it is a magnificent experience. But ya definitely pays yer money takes your chances.
Accommodations are fairly limited on Yap. The Manta Ray Bay Hotel is the most convenient for divers since it overlooks the docks and the dive shop is run by the same management as the hotel (i.e., Bill Acker, one of the most congenial hosts you will ever meet.). Down the way is Pathways and it seemed nice, but I found it a little dark and it not as convenient as the Manta Ray Bay Hotel. Up the hill is the recently remodeled Ocean View Hotel and it is splendiferous with large colonades, a grand entrance and lobby, and lovely pathways for pleasant afternoon and evening walks. We have not stayed there, but my guess is that the rates are high. However, it is gorgeous!
Yap is a small island and offers just a few "touristy" things to do. There are cultural events that are arranged by the hotels that will expose you to Yap culture, including cuisine and dancing. You can go to see the WWII Japanese airfield with its runway intact and just a few old airplanes and gun emplacements still around. (There is a wrecked 737, too, that made an incorrect landing and can be explored at will.).
There are a couple of shops that feature the work of Yap craftsmen and craftswomen. The models of Yapese outrigger canoes are especially appealing. If you are interested in a broad variety of excellent items, there is a shop within walking distance of the docks that has a wonderful collection. For the life of me, I cannot remember its name, but anyone can direct you.
The locals on Yap are amongst the friendliest folks you will ever meet on this earth. You can walk anywhere in complete safety and can strike up a conversation with anyone. That atmosphere is one of the true joys of being on Yap.
The Manta Ray Bay Hotel used to have Bill Munn as the chef. He has since departed to Palau. However, when he was on Yap, eating at "his" restaurant was an unforgetable treat. That said, I am certain that Bill Acker has sought a suitable replacement because he certainly recognizes the value of a fine restaurant on the premises. And I do not use the word "fine" casually: Bill Munn was a superb chef who ran a fine restaurant.
Pathways has a nice outdoor restaurant that we favor for lunches. They offer numerous Chinese and Japanese dishes that are just perfect for lunch--try their Yakitori! Dinner is also very good there: the fish, as might be expected, is fresh and grand.
The Ocean View also offers al fresco dining with a splendid and very pricey menu. They also feature the best wine list on island, but be prepared to shell lots of money--and they do not take any stones!
There are some smaller bars and restaurants and, after having taken a look inside, we chose to dine at one of the three mentioned above.
I think you mentioned that you were from Guam in an earlier posting. If so, you know all about we call "apple bananas", the 3-5 inch local bananas of Micronesia. We love them and usually have them for our breakfast fruit. On our numerous walks around the island we usually stop a small fruit stands and buy a bunch to use for lunches and snacks--yummie!
One more word on the diving: besides the Manta dives, you can reef/wall dive and we found the best diving to be outside the reef due to water clarity. Gilman Wall/Tip and Lionfish Wall were the best. I want to note that there was a typhoon that passed over Yap earlier this year and it devasted much of the coral: so be prepared for that.
Hope this helps,
Scorpionfish