Parc is a fun, bustling kind of place, but I was not too impressed by the food. I'm hoping to try Bistrot La Minette and Bibou soon, but just based on present experience, Zinc would be a better option. A very cozy, romantic little spot.
Is it too obvious to suggest Le Bec Fin? Bibou may have better food, but no other French restaurant in the city screams "special occasion" like LBF. Bibou and Bistrot (also good) are positively casual by comparison.
Bibou is the best French restaurant in the city, go there. If you can get a table, that is. They should still have availability during the week, but I doubt they have prime time weekend tables available.