Sounds like a fun trip. I currently live in-between Baltimore and DC. DC is defintely a walkable city for the majority of the sites. I agree, walk the monuments at night. Less crowds, heat and it's pretty awesome. If you're planning on driving around, DC is not the worst on weekends if you don't mind paying for parking. I believe Sundays are free on-street parking if you can find it. Garages are cheaper too, use parking panda and you can park all day for like 10-15 at many spots. Don't think you're going to come into town and see 3 or 4 museums in a day. You'll need to pick one and give it an honest effort. Do your research beforehand as there are plenty of fantastic spots to eat and drink. Baltimore is an interesting town, but less touristy than others. Inner Harbor is the main attraction since you have both the football/baseball stadium, surrounding bars/restaurants and the harbor. The main attraction outside of Camden yards is the Aquarium. Top notch if that is your thing and that is located on the harbor. If I was going to Baltimore for a road trip I would head to the inner harbor for some food. Walk over near the power plant for better fare than the stuff right at the harbor by the USS Constellation. Anywhere from shake shack to fogo de chao brazililan steakhouse is around there. If you go about two blocks past the inner harbor you will find Little Italy with some fantastic options. Most people visiting Maryland want crab cakes and you can get them in so many places. Everyone has their favorite spot, but I'd just go to trip advisor or yelp and find one. They are nearly all delicious. It's a lot of crab meat, so don't expect them to be cheap. If you like history, then Independance Hall and the liberty bell are must see. I'd avoid the whole cheesesteak adventure. Not worth the hassle to head over to Pat and Genos and find which one you'll like better. They are good, but not must see TV. And cheese steaks are all over the East Coast. I've had many that were far better than those two classic spots. It's a bit of walk from the Liberty Bell area and parking is rough. On street, jammed apartments. I would likely rent a car because I like flexibility and at the end of the day you'll likely spend close to the same on car/gas/parking/tolls as you would on all the trains combined for 2 people.