The Westin Tabor Center is a great hotel right on the 16th St. pedestrian mall in downtown Denver. It is truly central to everything you could want to see or do in the city. It is rated four our of five stars, and room rates average about $230 per night, depending on the date.
The facility is also well-suited for small conferences of up to about three hundred attendees. There are a number of nicely-sized conference rooms and ball rooms all centrally located on the same floor. The in-house catering is also very good quality (as one might expect since The Palm Restaurant on the first floor is a very popular "in" place to dine.) I appreciated the fact that there was free fast wireless internet available. I would definitely recommend this as a conference location.