I find the California Grill very romantic. The view is beautiful and you can go outside on the observation deck and enjoy wishes. DH and I had a great meal there.
I found on my trip this month that while I had good food and service, the places were not romantic as its a family destination. We dined at Le Cellier, Rose and Crown, Mama Melrose, and some others
Maybe you'll have better luck with a place even more upscale such as CG, and IMO, the later you can dine, the better your chances of quiet
Probably the most romantic moment we had during our honeymoon at Disney last month was on the observation deck at the California Grill during and right after Wishes. We had just passed the midway point of our stay and were beginning to dread going home. We didn't want to go back inside.
Yeah, it's a bit noisy, but after a moment like that you don't really notice the people around you. If you make ADR's, just try to schedule it for a couple hours before Wishes and hang around for it.