Aubrey:
The budget-minded, get-all-the-value-you-can-get-out-of-the-dining-plan side of me comes out whenever I'm asked about which Character Meals to choose at Disney: To get the most value out of the dining plan, your table service meals are "most valuable" when you use them at night for dinner vs. lunch or breakfast because, simply put, dinner costs more than breakfast at Disney restaurants and a dining credit is good for either.
However, we must take off our value hat sometimes when it comes to circumstances, in your case, a 3-year-old. In my experience, my children are their happiests, freshest, and best-for-the-camera in the morning. So I would heartily recommend booking at least one Character Breakfast during your trip. You've got many choices: Pooh & Friends at Crystal Palace; Chef Mickey's at the Contemporary; Lilo; Various Characters at 1900 Park Fare; Stitch & Mickey at the Polynesian; Princesses at Cinderella's Royal Table and Akershus; the Fab Five at Tusker House & Beach Club; and Playhouse Disney Favorites at Hollywood & Vine....whew!
I'd recommend choosing one based on the characters with whom you think your child will interact MOST. If you have several choices, I'd go with the meal that has a bountiful buffet versus a family-style meal with only a few choices (not best for picky eaters) and one that is in a theme park, so you can book early and get in to snap a picture with a background free of crowds--not taking up so much of your day. Top of my list: Crystal Palace.
For dinner, book an early reservation so that you can get a nap and then enjoy the meal before heading back to the parks. A bountiful buffet within a monorail-ride of the parks:
Chef Mickey's.
Wishing y'all a magical vacation!
Whitney