I can't speak to AF redemptions on miles, but I can tell you that if you are thinking NW is going to be better than CO, I think I'd disagree. If anything, CO's certainly been at least willing to sit down with people multiple times, and the EWR-Europe routes would give you great flexibility. Not that you couldn't accrue those miles on other carriers, of course.

If you can get a UK address you might want to consider it because I believe CO gives you a larger mileage bonus for business class flights if you are based in the UK.

Steve