I like the Georgetown area best for all kinds of eats, and given the student population, a lot of the places are pretty reasonably priced, believe it or not.
I've done the walk from GWU to Georgetown many times before; it really is not that bad at all, unless it is really sticky hot and humid (which, of course, it could well be). In that case, follow Scorereader's transit instructions.
In terms of eats...
I like Billy Martin's Tavern:
http://www.martins-tavern.com/ Been around for ages, nice atmosphere, good food, and good prices.
There is a Five Guys Burger also on Wisconsin Avenue, near Billy Martin's (I think you mentioned in another thread wanting to try the burgers here?).
I've always liked Pizza Paradiso on M Street (another one in Dupont Circle).
http://www.eatyourpizza.com/ I've always liked Booeymonger's sandwiches (only three local establishments; main location in Georgetown, near the University)
http://www.booeymonger.com/locations.html The homemade ice cream at Thomas Sweets (near P Street and Wisconsin Ave., near Billy Martin's and Five Guys) is sublime, IMHO. Well worth it (as the lines out the door will attest).
Hope this helps!
Note to Scorereader: I was going to throw in a recommendation for Nathan's in Georgetown for brunch, as I always liked the atmosphere and the food, and really found it reasonable pricewise...lo and behold, just googled it to find it closed this past weekend! What a loss.
<message edited by tacchino on Tue, 07/14/09 3:51 PM>