Had a friend of mine that did a very similar MR (specifically BAL-BWI-NCR-WAS-BAL) and you have to be careful not to miss getting your ticket scanned assuming you're doing multi-city on one PNR. If a conductor doesn't check you in on any of the legs, all the subsequent legs can be cancelled if enough time passes.

Besides that, it might be worth exchanging BWI for BAL and taking in a quick bite to eat in Baltimore. It certainly makes the breaks between legs more tolerable (though with the recent BWI pre-security renovations you might find it surprisingly pleasant to take a jaunt over there during your "layover")!