US Airways Dividend Miles - Upgrades

I am now silver elite on US Air. When traveling with a companion, do I book seperate reservations to try to increase my upgrade chances? If I book a reservation with them, will they not upgrade me automatically?

They will still upgrade you even your companion is on your record. As a matter of fact, they will attempt to upgrade you both.

When I travel with my friend (also a CP), we always book separately. If there is only one seat available for UG, then we know that one of us will get it, but if we are on the same PNR, then neither of us will.

They will upgrade you with your companion if the seats are available. If there's only 1 seat left, you'll get passed over for an elite by themselves regardless of who's ahead on miles flown YTD (the way status upgrade ties are broken at the automatic upgrade window). Also only works with one companion.