If you want to have great food, cool atmosphere and don't plan on getting too rowdy then California Grille
If you want great food and want enjoy good food but mostly great conversation and each other's company then I'd go with Ohana.
If you want a cool atmosphere where you can enjoy good food and lots of good drinks and live entertainment, then I'd go with Raglan Road.
If you want to do something really fun, then get a EPCOT passport book in the afternoon, and make your way around World Showcase enjoying a drink and snack/food at each country getting your passport stamped and have a picture taken with the CM that serves you each drink. If you do this, time it so you don't get drunk and that you end the evening with Illuminations.
Have a great time!