We have done Surf's Up several times, and it's our favorite. The interaction is really great. The interaction at the table is nice, but each time we go, my kids spend time with the characters after eating. There is an open area where they do surf/dance lessons every so often, and the characters hang out there when they aren't walking around greeting. My girls have spent half an hour or more just playing around with Mickey, Stitch, Donald and Pluto. Minnie and Daisy are also there, but have never spent extra time hanging out. The food is pretty good, too. We never stay on site at DLR, and we have walked from HoJo to PP where Surf's Up is. It's a trek, but it's not awful. We take our time and enjoy wondering through DTD.
Our second favorite is the Plaza Inn. It has a lot of classic characters like Minnie and Hook, but if your DS is only familiar with the Fab 5, then he might not know many of them. But it is closer (since it's inside DL) than Surf's Up.