This article does a great job of summing up Red Rocks, what might be the perfect outdoor music venue.
http://www.buzzfeed.com/danoshinsky/red-rocks-is-magic
This should be on any concert lovers bucket list. It doesn’t matter who you see, just make the trip, you will not be disappointed.
Muses from the front range of the Rocky Mountains
FrontRangeScribbles 
I had the opportunity to do some hiking at Red Rocks in July…..loved it and attending a concert there is on our list of must do’s!
It is a beautiful place to spend time at even if there is no concert