In reply to StefanB:
I did a month june/July time at CU Boulder a couple of years ago and found it the most amazing place.
It was 35 degrees at the time so to get out I got up just before the sun and this realistically gave me until about 9:30 before it got too hot.
Like Jonathan said, green Mountain is a lovely trail run. I didn't enjoy the Royal arch trail as much as there were too many tourists at the time, I guess it's one of the more accessible routes.
After building up the courage, one day near the end I soloed the first flatiron which was a lovely 1000ft plus severe on the way up but got somewhat lost on the descent, and ended up making up something a bit sketchy! The view from the top of the flatirons really is something though.
For something less active you can drive up flagstaff mountain and there is a parking spot at the top with some lookouts, that would be nice of an evening. There are some nice trails winding between flagstaff and green mountain there too and some quite hard bouldering if you are that way inclined.