Well, it's going to depend on the little boy. I have 4 boys and I have to say each has outgrown Pooh and friends by the time they were 4 years old. Well, the youngest is a baby, so I guess I can't speak for him yet. I wouldn't recommend it.
I just asked my 4 year old and my 6 year old, they both said Chef Mickey's. Not a park meal, but only a 5 minute walk from MK. If you must do a park meal, you should be OK with Garden Grill (dinner) at Epcot. You could do Tusker House in Animal Kingdom, but to have characters, you'd have to do breakfast. Rainforest Cafe (AK) can be kind of cool for birthdays, but no characters.