Thanks, those are both very good points. I just checked my M&M balance and I was off by a bit, I'm actually just shy of 30K, and they expire at the end of this year if not used by then. (The 40K I was thinking of were in AA, and those also expire in December.) As far as the timeframe, yeah, I realize I can't "replace" UA with CO at this point - just thinking about the future.

Also, if I were planning on going with CO as a *A carrier-of-choice in the future, it might (would?) make sense for me to join OnePass sooner rather than later, and (presuming I could maintain my NW status without them) credit my EWR-EDI flights on CO to that account, rather than to my NW account.

I haven't made my travel plans for the next 6 months yet, but given my probable travel patterns, I might be able to maintain top-tier elite status on NW and pick up bottom-tier elite status on either UA or CO. I'll have to see, though.