Actually, I feel US has cleaned up their operations pretty good in the last two years, and if you fly enough during the trial, you can be given top-tier/Chairman pretty easily.

http://www.usairways.com/en-US/divid...preferred.html

For UA, I shot an email to the status match email address, with a copy of my DL Gold status showing on delta.com (didn't have the card when I matched), and then flew a challenge. UA will match up to 1P/Gold. I will also say that Economy Plus (extra leg room) is an amazing perk, and keeps me loyal to UA.

AA will simply do a challenge up to PLT, if you have elite status already, they will give you GLD during the duration of the challenge which is a nice perk.

CO was a straight status match, can't say what they're currently doing.

AS is a straight status match, can accumulate on DL, AS, and AA domestically, and a bunch of international partners, but no upgrades on AA, and no waived baggage fees on DL or AA.