I've POE'd at PHX a couple of times (as a USC) as late as January 07 - It's not a huge deal there - Lines aren't huge as there aren't that many International flights into the airport I suppose.
You enter the Customs/Immigration almost directly from your flight (it may vary depending on the airline) - file through customs, then immigrations (there has always been a roaming officer who can answer questions) - then you get a cart, get your bags - walk a little, take a glass elevator up to the Passenger/Waiting area and you're done.
It's a big airport, but the good part is your sweetie can park in short-term parking, which is directly above the passenger terminal, so once your done, it's a very short elevator ride to the car.

(Sorry don't have any experience coming on a K1/etc visa - Karin came through as a tourist and had the same experience pretty much as me...)