For France,
First. I don't know your dress sense. When in France you need to dress right. Paris is a high fashion city and if you dress like a normal everyday tourist you won't get any pussy.
Second, if you are planning to get laid every night of the week then you will need some French language skills to game the locals.
Third, you are an American, I know for a fact that a lot of French girls don't like Americans. (No disrespect to the Americans here).
Fourth, you are going abroad for the first time so France and especially Paris might be too much for you too handle. Make no mistake, the French have an attitude and the place is not like you see in the movies.
Fifth, the place is expensive. Your dollar will be a worth a lot more in EE.
Sixth, the French have a fetish for Exotic things, just look at their cuisine. You guys will not be exotic not because there are a lot of blacks and browns in France but because there are a lot of Americans there. If you guys were coming from Brazil or Venezuela then you will get laid like kings. Damn I am starting to sound like an American hater myself.
Some French girls show a lot of resistance in the beginning but all of them melt like butter later. They are DTF but since its your first trip abroad I will suggest you go somewhere else or just go to Montreal.
I would suggest Finland (based of Subutai's feedback) and Iceland based on my own experience. Haven't been to the EE countries but it sounds like heaven judging by the posts here. The only thing that turns me off about the place is the skinheads problem.