The best option is to use any one of the Park 'n Rides scattered throughout Metro Denver and take the Light Rail or Express bus into downtown. If that's not an option, there are garages and lots ranging from pricey to not so bad. One thing to remember about parking downtown is that if you go out from the 16th Street Mall about 3-4 blocks, you can generally start finding parking for just a couple of bucks an hour. The reason I mention this is that the 16th Street Mall ride will take you the length of downtown for free, so no matter where you park, if you're within walking distance of the Mall Ride, it's convenient!
