re: Date in Baton Rouge

Go casual.

Roberto's = too much driving IMO. Stuck in the car for too long w/ a chick on a first date can lead to some awkward silences. "so uhhh"
French Market Bistro = Very good and one of my BR favorites, but depending on your age and her age I'd go more casual.
Tsunami = Nice date place, but sushi is always questionable on first dates and like you said, "it's been done".
Brandt's & Maison Lacour = Best food in BR, but not cheap and more than I would spend on a first date.
Bistro Byronz = Not too expensive. Nice date place. Large varitety on menu.
Chelseas = Very casual, fairly priced menu, good non-meat options. Can walk to another bar after.
Louisiana Pizza Kitchen = Low key atmosphere. Good pizza. Fresh food. Inexpensive and casual.
Marcello enoteca = Good food. Not overly expensive. Good atmosphere, but a bit loud. Can walk to the Bulldog for a beer after.
Thai Kitchen = One of the most overlooked places in BR. Great Thai and sushi if you think she's feeling frisky. And you can walk to the Bulldog.
Goodluck