What about in terms of recreation, accessibility to necessities (like...grocery stores) without a car, rent costs, etc. Things other than nightlife
Obviously, where you live really determines this, but my roommate doesn't have a car and she has never had a problem. If you were to move out into parts of VA or MD, it could become an issue, but generally, grocery stores and things like that cluster around metro stops, so even in VA or MD, if you live near one, you should be ok.
As far as rent, it is definitely expensive. Foggy Bottom near GW will cost you at least $2,500 for a two bedroom and not much less for a one bedroom. If you are thinking GW, places in Arlington (near Clarendon, Rossyln, Ballston) are definitely cheaper. You can also live in other areas of DC, like Columbia Heights, Adams Morgan, or parts of Capitol Hill for less, but you will probably have to sacrifice proximity to the Metro for cost.
Hope that helps.