It really depends on what your family likes to eat.
For ambience, I love the Coral Reef. We also enjoyed the food when we were there for NYE.
Chefs de France is also a great restaurant. The food isn't so ethnically different if you know what I mean- especially if you go for lunch. Now that Remy comes around to the tables- search the dis threads to see when he comes around- the restaurant has become even more popular.
Teppan Edo has AMAZING food and it's so much fun to watch. I loved Teppan Edo and thought it was a bargain for one table service credit. I don't know if you're on the
ddp, but I would consider this if you are.
Le Cellier gets a lot of rave reviews here. My family enjoyed it, but me, personally? I didn't see what the hype was. Sure, it's a good deal if you're on the ddp. But the food was typical of any steakhouse and the ambience didn't cut it for me. Also, with two daughters, the ambience in this restaurant is nothing to talk about. It's modeled to look like a wine cellar, so think close tables, kind of dark, lots of wood.
Really, I would highly suggest buying a WDW guide book (unofficial or official) at any of your local bookstores or B&N or Borders and perusing it. There are many great restaurants in Epcot that the dis sometimes overlooks.