I fly about 35K per year (2x to LHR, rest domestic USA). I've been Platinum on CO because of the DEQM offer in 2009 but next year I'm back to CO Silver status. As I'm also lifetime Gold on AA, I'm trying to decide whether to give up on CO/UA and switch back to AA. Which is the best for low tier elite fliers like me?

The only real difference that I can see between the two programs for bottom tier is that AA would allow me to book exit rows and CO doesn't allow that for bottom tier, only 2nd tier. Are there other differences that I'm missing?

Due to a job change, EWR and JFK are exactly equal for me and my particular destinations are all ones that both fly NS. And I don't see enough difference in coach service to make that a factor for me. I prefer to fly VS and BA on my LHR flights anyway.

Most of the discussions on this list seem to be about and by top tier frequent fliers so I thought it might be interesting to post a question for those of us in the lower mileage brackets, as it were