How would the commute be driving?
My biggest reservation is, as a woman, not feeling safe walking around my own city at night. I know Baltimore has come a long way but it still is not the safest of cities (for reference I've lived in Boston, NYC, and DC) and I fear I would feel a bit like a prisoner in my own town.
If you want to plan on driving from DC to Baltimore everyday, then I'd expect a 1:30 commute (maybe even 2 hours on really bad days) each way in rush hour. Having a car in DC will also be very expensive, but if you've lived there before, you should already be familiar with that. All cities have neighborhoods that are safe and neighborhoods that aren't. I've know a few girls in their mid-20s who have lived in downtown Baltimore for a few years and didn't say anything about not being safe. It's all about where you choose to live in cities and making smart decisions when you're out at night. My $0.02 would be to live in Baltimore.
I lived on the other side of DC in VA about 15 miles from my office in Arlington. It would regularly take me 50 minutes to drive to work and would cost $17 a day in tolls/parking costs. I would bike sometimes and it would take the same amount of time to get there.