I know a few guys who use to have crash pads in Detroit. A lot of them seemed to be west of the airport, out in Ypsilanti or Ann Arbor. They would go in with 4-8 other guys or so and rent out an apartment. You would need to have a car there, though. Ypsilanti is around 15 minutes from the lot and Ann Arbor is around 30 minutes. Ann Arbor is a college town with lots of bars and college chicks.
Another place I recall guys using was called the "Inkster house". It was located somewhere on Inkster road north of the airport. It is a pretty big house rented out solely for crashpad people, don't know a lot about it except it seemed like I knew some people that used it. Maybe some Mesaba or Northwest guys might be able to help me out here.
The other option is staying at the local hotels near Metro. That can get rather expensive unless you have a lot of guys in the room. The good thing is that you won't need a car. The hotel shuttle vans will run you to the airport. There really is not a whole lot to do around the airport, so I would definitely have a car. But if you are going to have a car than I'd say "Go west, young man!" Get something in Ypsi or Ann Arbor....you'll have more fun and there will be more stuff to do.
You need to call Dave Hill at (859) 356-3309. He's a NWA Airbus pilot who runs several pads around DTW. You can choose from a Condo with your own room or a standard pad in an apartment complex that has a shuttle to the airport. I stayed in one for a while, pretty good as far as pads go. He's easy to work with and knows a lot about the area.