If you have a non-diver, you definitely do not want to go to Yap. There is very little to do there besides dive. You can walk from one end of town to the other in about 10 minutes, and there are about 5 restaurants total, a handful of hotels, and some little stores, but that's about it. Some day activities for the non-diver would be kayaking, renting a bike, cultural tour, etc. Keep in mind also that there are only 3 beaches in Yap. The closest one is 45 mins from the main town. Awesome place to dive, but it might get pretty boring for a non-diver.
Palau may have some spa action going on at Palau Pacific Resort since it is a pretty sweet hotel, but I haven't been there in awhile.
I have no idea about Chuuk, never been there.