In the nice areas of downtown the prices weren't hit all that hard. DC real estate had been white-hot for the last few years, so maybe you could count holding fairly steady for over a year as a relative decrease.
If you get a fair deal in the market right now in the area you're looking to live in, I think it's highly unlikely you'll be in a position to take a loss at the end of 3-4 years. And as you said, you're building equity instead of throwing away 40k+ in pure rent.
Definitely do the research yourself. There's no subsitute for it. However if you want my two cents, I don't think you're taking too much of a gamble in that area.
The law center is on the Red Line, and our metro system is pretty damn good. So you can live near one of those stops and still have a pretty easy commute. The neighborhoods going west on that line are probably the most desired locations in DC. Metro - Rail - Maps - Rail/Google Map
To get your bearings on the redfin map:
Chinatown: fairly developed, decent night life and restaurants. Those condo's closest to the law center are probably going to be pretty nice a lot of them were constructed or renovated recently. You're probably not going to see a tremendous increase in the price of those over the general trend, but it's pretty stable. Good metro access, the chinatown stop connects to Judiciary square if you are feeling too lazy to walk and it's also a transfer for another line.
Penn Quarter: A little more established, and a little more sterile. I'd say good for an older, more buttoned down crowd. Probably the highest priced condos are going to be here, and probably has the least value. Chances are that more than one partner in your future law firm has a condo in this neighborhood.
Mt. Vernon: This is becoming more of a walk for you, but it probably has better deals. A lot of development is happening in this neighborhood and a lot of the condo buildings are new. It's next to some areas that are still pretty dicey (east of New Jersey ave), so it's a neighborhood in transition, but I think you may find greater appreciation on your investment here.
Truxton Circle I guess: Not sure if there are condos there. If things keep gentrifying and the owners of the public housing continue to let their Section 8 licenses expire, then it will be a great area... but not in 3-4 years.
Generally speaking, the further west you are, the better the neighborhood is in the immediate area.
If you start looking east, you are getting out of walking distance because Union Station and its tracks take up a large swathe of land. To the south is the Mall.