What a shame that your first chance to experience continental Europe is a few hours in Geneva, rather than almost any other European city of similar size. Geneva offers very little in the way of really great tourist sites, though I'd still go into town just for the ambience if I were in a similar situation. And as others suggest, it's also worth the trip in for the food, which can be quite good.

Paradoxically, if you had a few days rather than a few hours, Geneva would be a great place to land, because it's excellently situated for a weekend getaway to some of Europe's most spectacular locations. I've often said that Geneva is sort of the opposite of what people used to say about New York City: it's a place you wouldn't want to visit, but would love to live there.