Are you going to be in downtown for the conference? From downtown Denver, you could go north to Ft Collins and back, taking in as much climbing as you dare along the way. The most direct route would be around 70 miles one way, but there's no reason to be direct. Go through Boulder first and it's a great, well-travelled way to see the Front Range.
If you have some more details around how you want to camp/stay, I'm sure there are a few folks here that can get you pointed in the right direction...