Perfect for the Solo Traveler! Hostel Fish is walking distance from... everything - when you get off the plane, take the train to Union Station, even with luggage etc it is an easy walk to Hostel Fish, and the Train is cheap and easy to use.
I was in the "Maps" room - all of my fellow travelers were very quiet and respectful, the bed was comfortable and the room was the perfect temp the whole time. I am 6'1 and the bunk fit me well - you have your own light and little fan, a curtain for privacy. The bathrooms are kept very clean, showers are nice and you get a complimentary towel - shampoo and conditioner. I even used their blow drier. They let me do an early check in and were incredibly accommodating the entire time. Can check your luggage for after check out or prior to check in. One suggestion - bring your own pillow!
Fun spots within walking distance; ViewHouse Ballpark (esp on weekends, it's like a day club), 1Up Arcade Bar (any night, dive bar vibes), Denver Milk Market, Larimer Square --- you're also walking distance from Summit & Marquis Theater for live music --- Denver Art Museum is a bit far but worth the walk to take in the city.
There is a Bar downstairs, it can get rowdy but you won't hear a thing in the room - this hostel is a live-in-workspace, this includes both the front desk and the bar space. Tip your bartenders!