Thanks to everyone for their informative replies. I've been reading this forum for quite a long time, and it's one of the reasons that I would want status on AS over any other airline. It's great that everyone chimed in with good and friendly advice.
I'm going to go with UA, but that's mostly because my boss -just- told me that he might send me to a conference in Belfast this summer. CO/UA has a direct flight there from EWR and I might be within a MR of 2p by the time that flight happens.
I probably would have gone with UA anyway. The extra leg room from E+ helps my back considerably, and is free to 2p, rather than having to hope for upgrades (or burn too many miles). However, once my back heals and leg room is less of an issue you guys made a great case for going back to AS. Plus I'm a sucker for Alaskan Amber, even for $6.
Thanks so much for all of the great advice!