For a 1 TS restaurant, I would choose between LeCellier, Coral Reef, Spoodles, or maybe Mama Melrose. LeCellier has "been discovered"--a few years back it was kind of a quiet romantic spot, but now it is a very busy place--almost chaotic sometimes. Coral Reef is nice, but can also get pretty busy. Spoodles is out of the parks, and seems to draw a more adult crowd.
Believe it or not, for a pure romantic atmosphere, Mama Melrose isn't bad--it has the classic small Italian restaurant theme, and is not too loud. At least in the times we've been there, it seems to be a slightly older clientel than some of the other resort restaurants. A bottle of Chiante and the candlelit red and white checkered tablecloth and you are in business!
