There are lots of places, and the best way to find them all is go to
www.disneymeetings.com, scroll down to Theme Park Venue Map, and select each park. The maps have icons you can click for descriptions of the various venues and events. Disney does tons of corporate and other private events in the parks, so there are lots of ideas to choose from.
If you are flexible, there are some cool breakfast ideas before the park opens, like breakfast and a ride at Everest or on the safari. AK also has the Eel Pavilion in the Flame Tree Garden, which is fairly reasonably priced and can hold events during park hours.And there's Tusker House and Festival of the Lion King.
Epcot ideas: Canada Terrace, Great Hall of China, Norway Loft, Breakfast in France, the Odyssey, and the World Showplace (kinda huge), plus all the usual dessert party venues and the newer ones, like Africa and Canada's new IllumiNations viewing area.
At DHS, you can do dinner in the Beauty and the Beast theater, the prop shop, Hollywood Hideaway, the Brown Derby, under the Sorcerer Mickey Hat, on New York Street,
Pixar Place - a lot of these are pretty huge venues, but your planner can help you narrow it down to something that suits you.