You might also consider a character meal either at DL, DCA, or one of the Disney Hotels. The only character meal inside DL is the Princess breakfast at the Plaza Inn (end of Main Street). Character breakfasts are offered at all 3 hotels. There's also a character lunch and dinner in DCA (Ariel's Grotto featuring Chef Mickey) and a character lunch or dinner at Goofy's Kitchen at the DLH. I personally recommend Goofy's kitchen for food quality, variety, and entertainment, although it's a little out of your way unless you are staying at the DLH (you can take the monorail most of the way there). Most of the character meals are buffets (Ariel's is not a buffet), so getting up and wandering around is not a problem. In fact, sometimes the characters will rally the children together for a march or dance. While I like Blue Bayou a lot and kids usually do fine there, I think an antsy 3 year old might do better at a character meal. Teenagers might not like character meals as much, but my 14 year old DS still loves Goofy's Kitchen. Lunch is cheaper than dinner for most of these choices.
Another option is the Rainforest Cafe at DTD. Kids tend to keep pretty entertained there. It's located very close to the monorail stop at DTD.