I'm also a NOVA/DC guy, but I've been to Baltimore a lot. There is plenty to do in Baltimore and DC. If I was you, I would focus on Baltimore more this trip as we play Maryland later this year and on a regular basis. You can take in DC another time, but trying to squeeze in both cities might be a lot considering most of Saturday will be reserved for the OSU game. As people have mentioned, BALTIMORE CAN BE SKETCHY. There are plenty of great areas, but you can take a wrong turn and be in a bad area. If you stay in Fells Point or the Inner Harbor you will be fine. Also, we aren't playing the Ravens or Orioles, so we shouldn't have any rabid fans attacking us (I had batteries thrown at me while at a Ravens game wearing a Colts jersey).
I would suggest staying near the stadium unless don't mind taking/paying for cabs. Parking WILL BE expensive! They normally charge $20-$30 in the general area of the stadium, so I imagine it will increase. If you drink and love bars, you will LOVE Baltimore. They have a LOT of bars in different areas of the city, all just a short cab ride. I will do a more through write up on the different areas and bars sometime this summer. There's a couple great places bars near the stadium, including Pickles Pub. I think that Power Plant Live is a short cab ride as well. Its a big area that has a ton of bars and clubs. You can pay one cover and get into all the places (great deal if your into clubs/lounges). Two places we love here is "Howl at the Moon" and BAR Baltimore. If you get a big group together, I can get you in contact with the sale rep for Power Plant. You can do a "All You Can Drink" night for like $35 each or something like that. Outside the stadium is a "Ravens Walk", which I'm sure will be up for our game as well. Its an official tailgate area and with similar stuff like that.
The basball stadium is close to the football stadium, so you could also see a MLB game if you wanted (great stadium!). They actually have a designated scalping area to get cheap tickets (not sure if they do that for the football games or not). In addition to the places that everyone else mentioned, there's also the Babe Ruth (birthplace) museum, which only a few blocks away from the stadium.
If you are a gambler, they opened the Maryland Live Casino which is located near a big mall about 20 minutes away. You can drive to the University of Maryland Metro Station (30 minutes) and jump on the metro to see things in DC. National Harbor (40 minutes) always has great things going on and they typically have a beer and BBQ fest on Labor Day weekend. Virginia has AMAZING wine and some very beautiful vineyards (haven't been to any in Maryland, but I'm sure they are good too). There's a lot to do, depending on what you're interested in. Whatever you do, you HAVE to have some Maryland Crab Cakes!! AMAZING!! Like I said, I will do a more complete write up this summer.