This should be illegal
I am staying here as part of a large group (probably 350 rooms). When I arrived around 2PM the check in line was enormous, and I heard that rooms weren't available, so I left to do some other stuff in Denver. I came back at 5:30 to check in, take a shower, and get to a 6PM reception. There was no line at 5:30 so I thought all was well.
The counter person told me that no rooms of the type I had reserved were available. It could be up to 3 hours if I wanted to wait for the room type, or I could choose to upgrade my room. There were 2 types of rooms available immediately, one was $10 per night extra, and the other was $30 per night extra. I said I didn't care what room I got, but I needed it so that I could take a shower and get dressed for the reception. She said I should choose one of the upgrades if I wanted a room right away. I refused because even though it was only $10 I couldn't believe they were really telling me this. 
I asked to talk to a manager and she told me there was nothing they could do for me because if they did it for me they would have to do it for everyone. Ok, I don't really care, if you did it for everyone maybe my room type would be available. Finally she said she would check with her manager, and came back and said she could give me the upgrade for no charge.
Seriously, I couldn't believe this conversation. I have a reservation, it is now 5:30 PM, and they want to charge me to check in? How can this be legal?
I intend to talk to our meeting organizer to let them know this happened and make sure that if anybody else agreed to pay this upgrade fee that the hotel refund the charge. It is outrageous that they even came up with this idea.
By the way, the upgrade room is fine but nothing special. If I look in the right direction I can see some mountains, and I have a sitting area with a TV. Not worth even a $10 charge for a single person who doesn't plan to spend many daylight hours in the room.