Caveat: My experiences as a UA elite are several years old, so things may have changed.

My last time traveling regularly for work was in the 1999-2002 range; I then had a non-traveling job, and starting at the end of 2005 I started traveling extensively again. During that last stint, I went 100% UA; for this one, I've gone 100% Alaska.

For me, when I'm traveling like this, I'm more interested in how they treat their elite members than I am about redemption possibilities. I think Alaska wins on that. I like the idea that upgrades are automatic with AS; on United, there was always a cost/value equation of "do I want to use my upgrades for this flight or save them for another flight?"

I haven't had any real "nightmare scenarios" with irregular ops yet with AS; UA always did a good job taking care of me when I was a 1K over there and things went to .....

My favorite thing about being an MVPG, though, is the waiver of the $50 change fee. That, alone, makes my life 10x easier. I will often want to plan personal weekend trips a few weeks or months in advance, but I also know that my work schedule can throw all of that into disarray. Not having to deal with change fees makes it that much easier to change plans. It's great for work, too, though the change fees aren't coming out of my pocket.