If you can swing the American SouthWest I'd definitely recommend the Canyonlands area...and all of the 4 corners area in general. I've climbed Ayers and The Olgas and they don't even compare (other than the sheer oddity of Ayers) to the ASW imo. It's the most beautiful place I've ever been to.
As far as cities go, I'll echo
FFL's Chicago suggestion. I'ts definitely my favourite American city. Austin is great too. I lived there for 4 or so years and it was fantastic. But outside of that you really don't need to visit Texas (no offense to Texans, but c'mon, what else
is there in Texas?
). New Orleans is great, and great friggin food to boot.
I just sent the SO to Spain (Barcelona) to get her out of my hair for a couple weeks and she came back raving about it. I trust her aesthetics second only to my own, so I'd have to plug there as well.
I love Toronto. My favourite Canadian city (though, I've not been to Vancouver, and everything I hear about it sounds like I'd like it). Rambling...sorry. Need more coffee.