My wife is going to grad school in Tucson, I am buying a new bike for around $1700-2500, what bike would you suggest???

I'm 6'4", love singletrack and have never ridden in Tucson. I'm interested in 29er's, but wouldn't want one if it is tight technical singletrack, but if Tucson is like I imagine (flat & fast) then a 29" singlespeed might be perfect. How about full suspension? I really like the simplicity of hardtails, but if it is really rocky then I might go dual???

Imagine Logan Canyon or Blacksmith Fork . . . if you call that flat, then your imaination is very good
While i am not an off-roader, throw lots prickly cactus into the mix and up the temps 20+ degrees.

I definately do not consider logan canyon or blacksmith fork flat, at least not in terms of mountain biking. Most trails in logan canyon go uphill for seveal miles and then you turn around and bomb back down. I've been looking at the Gary Fisher Paragon (Geared 29er, $1800), all of the Niner bikes (but I'm certain I would blow past $2000 in a hurry, Jamis Dragon 29 ($2000), Voodoo Dambala (i think I could build this up as a 1x9 for around $2000 with a fox fork???) or maybe I'll look at a steel 26er.