Well it depends on what your interested in and how much time you have.
If your just looking for stuff in the evening after CEDIA, there is 16th Street Mall, which of course runs on 16th street between Wynkoop and Cleveland. It has sports bars like the ESPN Zone and of course shopping. There are also a bunch of sports bars right around Coors Field on Blake St. and the surrounding area. In fact, you could probably find some cheap tickets to a Rockies game at Coors Field if thats something you wanted to do.
There are all kinds of restaurants so just ask a dude on the street and they’ll tell you whats up.
If you have an afternoon or day you can dedicate you could go to the Six Flags: Elitch Gardens amusement park. They also have a waterpark section there that I think is included in the price.
There is also the Denver Zoo, the Denver Botanic Gardens, and the Museum of Nature & Science which usually has some cool exhibits.
If you have a rental car or other means of transportation, there is a lot to do in the surrounding parts of Denver.
There is the largest, if not one of the largest, water parks called Water World at Federal Heights if your looking for stuff in the sun or if you have kids accompanying.
Right against the edge of the mountains there is the Red Rocks Amphitheatre in Morrison right behind Dinosaur Ridge. Its the largest natural amphitheatre in the world and very cool. There is almost always a concert held there.