Spirit of Aloha is an experience -- you don't really go for the food (IMHO). Personally, I think it is worth doing once for the experience; while the wrap-around story is hokey, there is some truly amazing dancing and the fire dance guy is fantastic. Book as early as you possibly can, as it is my understanding (from cm) that the earlier you book, the better seat you get. Again, personally, I wouldn't bother with a last-minute booking since sitting way in the back *probably* isn't worth it.
We love the Crystal Palace and go at least once every trip. Great buffet (we think it's the best on property) and wonderful interaction with the Pooh characters.