One of the differences between the DC program and living back on campus is that there are no dorms in DC. So instead of deciding whether to live in North Quad, Mid Quad, or South Quad, you instead have to decide where to live within Washington, DC (or possibly outside of Washington DC). I lived in an apartment with Carlos and Jenny. You can see a video of it here.
There are several different options you have to consider:
Is it furnished?
Are utilities included?
Is it close to the CMC Office (Corner of 17th and L Street NW)?
Is it close to your job?
Is it close to the Metro?
Is there a supermarket nearby?
Can it fit everybody you plan to live with?
Is it in a good part of town?
The apartment we lived in had been used the semester before by some CMC students while they were on the program. I highly recommend doing this. It is helpful to know from someone more trustworthy than a random landlord whether or not the apartment is any good.
In addition to our apartment, there were two more groups of three people, one living fairly close to us and the other living in Southeast near the Capitol. There were then two people living on their own, Ben F. lived in an apartment in Virginia and Mike Whatley lived in housing provided by the Heritage Foundation (although you don't have to actually work for Heritage to live there, as Mike did).
It is best to get a furnished apartment (as everybody this semester did) because you do not have to worry about buying or renting all the furnishings for the apartment. That can tend to get more expensive than you might think as me and my apartment mates discovered this summer. You have to remember plates, silverware, couches, tv, lamps, sheets, beds, etc..