I would avoid most of the "top tier" WDW restaurants - the atmosphere tends to be a little quieter and the service a little slower.
Ohana's and Whispering Canyon are both noisy, loud and fun.
In the parks, our 2 1/2 year old did well at San Angel Inn and Marrakesh (she danced with the belly dancer - quite charming).
Characters make dinner appearances at Chef Mickey's and Garden Grill.
The fish tank at the Living Seas is supposed to be good at keeping kids entertained.
Consider whether you are a buffet parent or not. After two WDW trips with small children and a
Disney cruise, we've pretty much decided we really really prefer not to have to balance our own food and our childrens and jump up every time picky eater wants more grapes. Other parents like the freedom and the chance for Junior to get out of his seat and "help."
Some hints - look over the menus before you go (or as you are waiting to be seated) so you can get moving right away. Let the host seating you know you are traveling with someone with a short attention span - usually Disney CMs will bend over backwards to get your courses quickly. Consider eating just an entree - and having dessert in the parks afterwards on the go, although if your DS is still doing fine when the entree is finished, you can certainly give dessert a whirl! We discovered our kids had been so busy all day they were surprisingly well behaved for dinner - even as toddlers. However, other parents discover their kids have been over stimulated and are in full tantrum mode by mealtime.