So to close this out, here's what I decided on:
- Prioritize AS and try to maintain 40K mi. on their metal. The 4 one-way guest upgrades are nice for family.
- Fill in w/ UA and AA when the schedule means that it's significantly easier on the family (or me, if it's a busy week).
- Buy an E+ subscription for the family when on UA (since we typically do 3-5 one-ways per year on UA).
- Keep my UA/AA credit cards for Admirals Club and United Club access when flying UA and AA.
So I figure I'm paying an extra $2K or so as "insurance" when flying on UA and AA, which I figure is reasonable.
The main reason for this, BTW, is b/c Gold and Platinum simply don't seem to offer much to make it worth maintaining those. I fell from EXP to Plat this past year, and got upgraded maybe 1x out of 5-6 trips; so it's basically just about early boarding and MCE seats. I'll miss free early MCE seats as AA Gold, so ironically, that will tilt me toward using UA more since I plan to get an E+ subscription. But b/c UA has better routes out of SFO, and aiming for 2MM status on AA seems like a ridiculous quest, I think that will work out alright.
The only nagging thing in my mind is that I might regret not centering on UA to get 1MM status, so I'll try this configuration for this year, see how AS delivers, and then re-evaluate at the end of the year.
Thx everyone for your help!