Even if they aren't on the same PNR, I have never had a problem bringing one companion with me in the first-class checkin line or for preboarding. Many times on AA.com, I find two separate PNRs to be cheaper than 1 PNR with 2 pax. Also, there have been times when I've used miles for the non-elite traveler's ticket and paid for my own, and had no problems.

Also, even on two PNRs, the AA Plat phone agents will "link" the records and allow the non-elite to sit next to you in the exit row, if you so desire.

United, on the other hand, has refused to link PNRs for me, relegating the non-elite passenger to the back of the plane. They also have thrown fits when I've brought a non-elite into the first class checkin line. Because of this, I always fly AA when I'm with a friend or family member that I want to make sure has a pleasant flying experience.