If you'll mostly be traveling to Asia, I would suggest accruing miles with either AS or NW as AA's Asia service is currently limited to NRT (although you can earn miles on both JL and CX). Also, AA has a n/s SEA-BOS flight on which you may earn AS mileage:
AA189 BOS-SEA DEP 9:30 A ARR 12:34 P 7X
AA188 SEA-BOS DEP 1:45 P ARR 9:51 P 7X