I spent six nights at the down-town Denver Courtyard Mariott and highly recommend this hotel for your Denver visit. My original accommodations fell through and I was scrambling for a place to stay. I was so pleased with this choice. The staff were very pleasant and helpful. The room I had had two queen beds and a very high ceiling. The sink area had a nice long counter with a separate room for the toilet and the tub. Free wifi. Very comfy bed.
Right outside the door is the city's free bus that runs down 16th. I was able to get from the Convention Centre to the Pepsi Centre easily and quickly. Walgrens just a block a way and lots of restaurants to enjoy nearby. Rialto restaurant attached to the hotel and you can get a coupon from the desk for this restaurant. I recommend Sam's next door as well.
This hotel does not have a pool or free breakfast but don't let this stop you from staying here. It is wonderful.