Been to Summit and Yamashiro. Both good suggestions but I like the food at Summit better. But better than both of those is Orange Hill in Orange. They have a nice patio to sit out and have drinks and I enjoy the view better.
Aroma Cafe isn't as romantic or classy but certainly a good place to go socialize and girls love the desserts. Something that would be more fun would be a place like one of the many Gyu Kaku restaurants where you can grill some meats and interact more with each other. They also have an awesome happy hour...