Some people say that their children do very well with the face characters (princesses). When we went in 2008, my youngest was 14 months old and my older one was 3 and a half. They did much better with Mickey & Minnie than the face characters. We had done the dinner at 1900 Park Fare, which was very nice, with Cinderella, Prince Charming and the step-family. My kids were shy around these characters since they talked!
Back then, Liberty Tree had characters and my little one was completely enthralled with Minnie Mouse! He couldn't stop staring at her!! He was rubbing her nose when she came over to the table and he gave her a hug.
I know your little one will only be 6 months when you go and won't remember it, but that doesn't mean that a baby can't still have fun. By that age they are smiling and giggling already! The memories alone are worth it!
All that said, good places are Biergarten (there is music, and great food too!), Liberty Tree Tavern has a nice atmosphere and food is served family style, fast service too in case you have to get out fast, any of the regular resort restaurants are probably fine too (GF Cafe, Captain's Grille, Kona, etc.) and they usually get pretty good reviews on the food. Boma is a nice choice, buffets can be quick if you need them to, so you will enjoy that. AK Lodge is also a beautiful hotel!!