Hi Christy!
Your son is in for a magical treat when he visits Disney for the first time. And everything is magical at that age isn't it? So Disney is gonna be a blast for him!
I took my son at 2 1/2, and his favorite character meals were:
Check Mickey's at the Contemporary Resort (Starring Mickey, Minnie, Donald, Goofy, and Pluto)
Hollywood and Vine at Hollywood Studios (Starring Playhouse Disney Characters and my son's favorite, the Little Einstein's)
Crystal Palace at Magic Kingdom (Starring Winnie the Pooh, Tigger, and friends)
So any of those I think you won't go wrong (although my son was a little nervous with Tigger, and had to warm up to him)...but all the others he was OK...
Best wishes for a magical time with you and your son!