valentine's day dinner in st louis near wash U
Since you have a car, distance isn't as difficult a criterion as "romantic" and "not terribly expensive" since I don't know what qualifies for each. I know as an undergraduate, my standard was somewhat different from what it is now.
Here are some possiblities...
More young and fun feeling:
Taste, which is a small plate place in Central West End, that's got a nice feel and you can control pricing: http://tastebarstl.com/
Brasserie by Niche, next to Taste in Central West End, that's got a lively and bright feeling but the food is a little more substantive: http://www.brasseriebyniche.com/
Sen Thai, downtown and not fancy but a pleasant spot and budget conscious: http://www.senthaibistro.com/
Rasoi, Central West End Indian in a pleasant room and not too expensive (quite near Taste and Brasserie if you go resie-free): http://www.rasoi.com/
More established and likely expensive:
Atlas Restaurant, standard Frenchy Continental and walking distance from Campus, nice room though not spectacularly "romantic": www.atlasrestaurantstl.com
Five Bistro, which is in the Hill, a bit more expensive and creative: http://fivebistro.com/index.html
Truffles, in Ladue and relatively close to campus, but more expensive and older feeling: http://www.trufflesinladue.com/food/
Niche, one of the more expensive places in town but likely to have a nice meal and it's a great room: http://www.nichestlouis.com/home.html