Have a buddy in my reserve unit who was "hired" by UPS in 2002 and sat in the pool for about 2 years. It was his absolute first choice so he didn't apply or interview anywhere else. Well, when brown did call him back, they brought him down to Louisville and basically re-interviewed him. You can guess the rest of the story. Didn't have a good day in the sim and they said thanks but we're not interested anymore. A job offer, a class date, none of that sheeot means anything until you're sitting in Indoc looking at your employee number.
I say go with SWA or CAL, then make your decision when UPS calls you back. Needless to say, it's a nice problem to have though.