Paris is probably my favorite big city these days, but you sure don't get a lot for your birthday-celebration buck there. If the weather is nice, put yourself together a romantic picnic, find a nice spot along the Seine, and kiss a lot. See if you can outdo the French in this popular sport.
There's a lot of great take-out food along Rue de Sevres - quiche, rotisserie chicken, all kinds of pastry, plenty of wine. Lots of other neighborhoods have these kind of shops too, but you might not find them without guidance. There's quite a bit of concrete along the Seine too, so someone should help you pick the ideal picnic spot.
Visit Paris for the romance. Defer your celebration dollars until you get to Los Angeles. They'll go a lot farther here.