Kona- I've only been there for breakfast, but food was great. If you guys are coffee drinkers, try ordering some Kona Coffee if you can. It is like Heaven in a cup. Seriously.
Sci Fi- That's one of my favorite restaurants at Disney. I love what some of the other guests do as they're watching the old horror movies. It's hilarious-and the food is quite good too. I like the milkshakes too. We're going to be eating there again as well when we go back in June.
Liberty Tree Tavern- I like it there. We went for dinner last year and the food you get is a lot like the kind you'd have for Thanksgiving/Christmas dinner. I think it's different for lunch tho...but they have food like a cheeseburger and pasta on the menu for then so...yup.
If you want a really fun place to eat at- I'd suggest 50's Prime Time Cafe. The servers act as if they are your aunt, uncle, cousin, etc and reserve the right to 'discipline' you if they feel the need. My father once attempted to throw a paper airplane at our waitress and he was forced to put his nose to the wall. My sister also got a 'Queen Tattle Tale' hat made out of the kids menu for telling on him. And, thanks to my mother's big mouth, the waiter played 'airplane' with me because I hadn't eaten all of the food on my plate the last time we went...
It's fun tho. Lots of picture opportunities.