If you can get the AA online booking bonus go with AA (either way, try to get the online booking bonus, I believe right now AA's bonus is better for the first booking). As mentioned they relaxed expiration policies too, so edge is with AA. Both UA and AA can be transfered to HHonors, right now because of the promotion they are the same, but eventually AA to HHonors conversion will not be as good as UA to HHonors.

[This message has been edited by pgupta011 (edited 08-04-1999).]