I went to CO last year; stayed near Denver at 5,000 or so feet for a couple days. Next night camped at about 8,500 feet and really noticed it. I could go day hiking around the campsite pretty well with no problems, but if I sat down on the ground and got up or sat in a lawnchair and got up it made me really dizzy. Anything from a low position and getting up. I think by the end of the trip I was doing OK at the higher elevations.

sdmc530...You'll have fun out there. Can you squeeze in the Badlands which is not too far away?