That's what I do, Platinum on AA, MVPG on AS, all done by segments (150 total segments this year.) You get the best of both worlds. I was on track to making EXP on AA, but my flying slowed down considerably the last quarter of the year. If you're serious about doing both, it's not very difficult to add a SEA-PDX segment on most of your west coast flights to bump up your miles and segments.