Take it from a former local, the best hotel in Denver is The Oxford. I took my wife to The Oxford for her 21st birthday weekend and they made us feel like we were high rollers! I have never forgotten that and always return here! I love this place.
The rooms are all decorated differently with antiques from different eras. Each room has its own attitude and view. Most rooms have a view of 17th St. or of Wynkoop St. (There are "interior rooms" that have no view and may not even have windows.) There are some rooms with these huge soaking tubs that I highly recommend. No matter what room you get, you will be happy.
McCormicks Seafood is also attached to the hotel. (President Clinton loved McCormicks.) I have written a review of McCormicks, but suffice it to say that there is no better seafood in Denver and no better brunch either.
I used to go back at least once a month to the Cruise Room, which is a cool former speakeasy also attached to the hotel. They have awesome drinks and a great staff. Say "Hi!" to Jennifer in the Cruise Room and Dex as he valets your car at the Oxford! This entire building needs no help charming you, but the staff also kicks @ss and will go above and beyond your expectations.