Well, how much you want to spend, time and money? It takes 6 hours to fly from the East Coast of the US to the West and a goodly bit extra money.

Colorado and the West has the "best' outdoors but there are nice mountains, the Great Smokies in North Carolina/Asheville, as Timgt5 says. You could go to Nashville, Tennessee, get a little country music while you're down that way :-) http://www.tnvacation.com/

That's an idea; all the states have travel brochures; I'd find a list of states and find websites that have a way to have them send you their brochures. That will give you reading material.

Everywhere has outdoors that's gorgeous; coast of Maine, barrier islands off North Carolina and Florida (Key West), and it's all different. If you're going Fall, you have to do New England, see the leaves change: http://www.capetrain.com/ http://www.conwayscenic.com/ http://www.rails-vt.com/