Sherman, September in the Rocky Mountains is a wonderful experience.
The national parks aren't full like they are in the Summer, and the weather isn't too hot.
You could fly into Vegas, then drive to Southern Utah and do Zion for two days and Bryce Canyon for two days. Great views, and if you are a hiker you will love it.
Aspen and Vail are awesome as well. Fly into Denver, and drive 2.5 hours. It will be off season, so rates will be reasonable.
Tahoe is another fantastic option. Fly into Reno, spend 1 night, then head for scenic Tahoe. Bring backpacks and your camera.