Just got back from a weekend in Denver. I was originally going to rent a car, not that I really needed it, but it would have been way less than a taxi, and I would have had it handy if I wanted it. Then I saw that the hotel downtown was charging $25/night for parking--cancelled that car right away! Ended up taking the SuperShuttle ($19 o/w as indicated above)...might have been able to do the SkyRide, but it didn't look like my hotel was near the route (didn't catch the bit about transferring to the light rail until reading this now) and I didn't want to drag my luggage along for however far.

And never would have wanted the car at all--would have been *way* more of a hassle, even if it had been free.