There are alot of buffets and yes they are all you can eat. Off the top of my head Tusker House at AK for BF, L, D (characters at BF) Hollywood and Vine at DHS for BF, L, D (characters at BF and L), Chef Mickeys at Contemporary Resort for BF and D (characters at both), Cape May for BF and D (characters at BF, clambake seafood buffet at D) Crystal Palace in MK (I believe BF, L, and Dinner but someone correct me if I'm wrong. I know characters are there for BF not sure about the other meals) 1990 Park Faire at Grand Floridian for BF and D (madd hatter, Alice, Mary Poppins etc. for BF, Cinderella, Prince, Stepmother and Stepsisters for D) Biergarten German buffet in Epcot for L and D (German music and dancing) Askerhaus in Epcot has a cold buffet and plated entree B, L, and D I believe ( I beleve Princesses at all three), Boma is an African Buffet for BF, L, and D. Ohanas has all you can eat breakfast platters delivered to your table and meat skewers brought around at D (Lilo and Stich at BF)
Hope this helps.
We have only tried Hollywood and Vine D, Tusker House BF, and Chef Mickeys D. We liked all three for different reasons but our favorite was Tusker House. Adventurous stuff for mom and dad old favorites for the kids. Lots of variety and fresh.