OAK has no elite security lines, even if she somehow earned MVPG. This is the exact type of passenger that should be Gold, but won't be under the new scheme of things. In fact, this is the alienation of the core customer base.

All that said, I'd still choose AS. First, what will you do with the "3 WN Free Tickets?" If you use them SEA/OAK, its a waste. Also once she hits MVP, she is eligible for free, albeit rare, upgrades. On OAK/SEA, depending on time/day of travel, they should happen from time to time. No charge, no certs needed. The miles earned will be good on a lot of airlines, and by doing the "start up" things (first time web booking, first time web checkin, first time kiosk checkin, credit card, etc. bonuses), the miles will rack up quickly, at least in the beginning.

Also, if you have status on UA, ask for a match at AS. It will mean she'll earn 50% bonus if she gets MVP.

Also, if MVPG is a "goal", she can always do an occasional SEA/PDX/OAK, which will rack up some extra miles, and if there's a segment promo going on too, another opportunity for segs.