I agree about WCC being a little too noisy. I think on a first date you'd like to be able to have a conversation, and get to know each other. I also agree that Beaches and Cream or 50's Prime Time would be great choices. They're both informal, not too expensive (by Disney standards anyway lol), and have good food. 50's PTC of course would be more "fun" but the atmosphere at B&C is great too. We love Sci Fi but it would definitely be more intimate than the other two. For one, it's dark in there. Also, you would be sitting side-by-side sharing the same seat, rather than having the option of sitting across the table from each other. My family loves Sci-Fi, but would you -- and would your date -- be comfortable sitting right next to each other?
Coral Reef would be nice, especially if you could get next to the aquarium, but it's also more expensive.