Just an fyi...no characters at Ariel's dinner.
May I suggest a Blue Bayou lunch? The menu is a tad cheaper, plus you can reserve a table for opening and have a good chance at getting a waterfront seat. It's worth the additional wait, especially for your kids.
My suggestion for a character meal would be Minnie's at the Plaza Inn. You can get an early reservation during a Magic Morning. This way you won't miss any park time. The amount of characters are significantly greater at this experience than any other. Storytellers will have four characters, while Minnie will have a dozen at least.
Lots of wonderful counter service options at DCA. There is Test Pilot's Grill, which has good bbq, like Flame Tree at AK. It also has a fixin bar like Pecos Bill's. There are two large sections in the park that offer a cluster of choices together. Like Sunshine Seasons, but on a larger scale. One offers Italian and Mediterran choices. The other (my family's favorite) offers a bakery with soup and salads in a fresh bread bowl, Chinese, or Mexican counter service.
BTW... my top choices for table service (with our children) would be Cafe Orleans, Carnation Cafe, and Minnie's Breakfast.
Hope you have a magical trip!
