Being young, presumably, and having good lungs acclimated to the altitude, you should do just fine with a 48/38/26 crank and a 11-32 cassette. I climbed, very slowly, Wolf Creek and La Veta Pass with a 30 pound load with that combo and I'm old with poor lungs.
As for the bike, I'd strongly consider a Trek 7.2 FX. Reasonably priced, versatile, comfortable, and reliable. Or a road bike with trekking gears. Just make sure what ever you get fits you well. Fit is First.
Last edited by Cyclebum; 05-13-10 at 10:51 AM.
Reason: correct typo. thanks BWF.