Another vote for Chef Mickey's. We took my nephew there for his 6th bday and it was a HUGE hit. We loved the food (breakfast/brunch time), the characters, napkin waving, nephew danced with Donald, monorail running overhead, very memorable and fun time.
I had noted the bday in the ressie and we had a first night dinner at Narcoossee's. We were seated and given menus, much to our shock the menu had been personalized with a birthday wish for my nephew, sweet. He wanted to know how that happened and it was so fun to tell him "Disney magic" on his first night ever at WDW.