One thing that I found extremely helpful when my son was younger, and pickier, was to have a game plan. The most annoying thing was to walk up to restaurant after restaurant and not find anything he wanted to eat.
Prior to our second trip to WDW, I sat down and reviewed the menus for each CS in the 4 parks, and made note of which offered items he would eat. Then I printed the name of the restaurant, location(i.e Adventure Land) , and the picky approved food items that were available on index cards. I made 4 cards, one for each park, and laminated each (packing tape). The morning of, I grabbed the correct card and put it in my bag with the rest of my planning info. It was a lot of work up front, but having the information on hand when we were deciding where to eat was priceless.
Lisa