Originally Posted by
Yllanes
I liked the Hilton Old Town Alexandria. Right next to subway and trains, very convenient from DCA, restaurants in the area and good free breakfast buffet including cooked to order items.
Edit: Looks like I misread the OP and they want to stay in DC proper. I still would probably look into Alexandria because it's cheaper and an easy subway ride to the attractions.
I concur with Yllanes. If you're willing to be a little bit south of DC, the Hilton Old Town is a good property. I've been spending about 80 nights per year there for the last several years, so it's like my second home. Besides being easy to get to DC, it's a reasonable walk or free trolley ride to the Old Town Alexandria area near to the river, featuring lots of restaurants and some sightseeing opportunities.