Weekend traffic is better - during the week off rush-hour times is also reasonable enough too, though there is always a chance that it might suck. Depending on how many people you have, driving in is sometimes cheaper than metro. I used to always just take metro into DC, driving to the outlying station, but once we hit 4-6 people, it just stopped feeling as convenient - also when I'm done seeing the sights, I want to be headed home and taking the train and then driving feels like it prolongs the feeling of "I'm done and just want to leave". Or maybe my tolerance for driving in the city increased too, it was rarely all that bad (as long as I wasn't doing it during rush hour/s).
For Baltimore things:
The AVAM - American Visionary Art Museum is interesting.
I like the Aquarium too, the price tag is steep. You can go for half-price on Fridays after 5pm but then you're only getting 3 hours to look around. We've always filled an entire day looking at things there. They have some homeschool classes, probably not in May though, that give you free entrance with a paid class, that was always when we'd go because I could get in free, the kids would be in a class for an hour or so and then we'd get to enjoy the aquarium.
I like the Science Center too for kids. And then wandering around the inner harbor enough.
ran of time to post more...
Edited by xixstar, 20 January 2018 - 09:40 PM.