Jiko, Artist's Point, Bistro de Paris are nice; Yachtsman is ok. San Angel Inn has a fantastic ambience but the food is only average.
NOT California Grill. It is not a romantic setting at all. The view is nice, but that's it. It's just a noisy, open, hectic restaurant with a nice view.
Only Victoria and Alberts requires a coat/tie. Any other Disney restaurant you can walk in wearing park clothes if you want to do so.