I know little about it, though I love going :) City Park Jazz is every Sunday from the end of June to the beginning of August. Rain or shine. Check out
http://cityparkjazz.orgIt's a great place to sit on a blanket with friends, enjoy a glass of wine (in a plastic cup as glass is not allowed in the park), and people watch. If you are seated at a distance from the stage, the jazz is more ambient than anything, but it's a nice back drop. There's a different band every week. If you look at the City Park neighborhood on this site (
http://social.homesincolorado.com/city-park-denver-denver-county-colorado), I posted a brief video from a couple of weeks ago.
One cool thing the last couple of years is that they've started bringing in food trucks, so now you can get dinner right at the park. The event has been growing year over year. Parking in the neighborhood is a challenge, so it's worth taking the bus a little early, or if you're willing to walk a few blocks, park South of Colfax and walk up to the park. Just watch out for resident only parking areas on the streets. They ticket like mad during Jazz in those areas.