My personal limit is two days for each park, that's my limit.
Day 1-MK Columbia Harbor House, upstairs
Day 2-EPCOT (used to love the Electric Umbrella, Alfredos) Das Biergarten!
Day 3-MGM Backlot Dining, Sci-Fi Cafe, Prime Time Cafe, Pizza Rizzo
Day 4-AK Pizzafari, sit in the back room...