I'm going the A3 route myself...but that's because I know I won't fly 50,000 miles this year on a *A carrier.

I'll have the baggage allowance, priority checkin/security, lounge access, and preboarding, but probably never any upgrades unless I buy 'em. Partner elites don't score too many freebies when it comes to upgrades.

If I thought I had a legit shot at Star Gold on the actual metal I flew most often, I would be putting my miles there.

Note: A3 also has some funky rules on what fares count for 100% tier miles. Most of the common leisure fares on UA are 50% qualifying. On US, they're 100% Check your own likely carrier(s) to see what counts and what doesn't.