Get in real good shape - then get in better shape! You will. Be working with at least 1/3 less oxygen in the air and a lot less humidity. Those are both pretty rugged areas, 42 not quite as bad and also right along I-70, so a bit easier to get to. If I remember correctly, both are about the 6,000-8,000' elevation level with a lot of straight up and straight down. You can get area maps that list public and private lands. Expect temperatures in September to be in the 80's during the day and below freezing at night, and dry conditions, unless there is an early blizzard! If we get a "normal" rainfall, and feed is available, the elk will likely be up high. Area 72 is in a severe drought right now, 42 isn't much better.
Good luck and good hunting! I should be getting some info from CPW soon regarding forecasts, so I will try to relay any pertinent info.
Hawkdancer