Clean efficiency gym. It's open 24/7, and is only staffed occasionally - you enter via a fingerprint scanning system. You can sign up for a trainer... or not. So basically if you time it right, you can go to this gym without speaking to a human. Excellent choice for the generally awkward.
They've got treadmills, stairmasters, spinner bikes, free weights, mats, some exercise balls, and an assortment of machines. A few TVs on the walls and ubiquitous motivational house music on the stereos, but fortunately nothing too distracting to prevent you from zoning out to your NPR podcasts.