Phyllis, Its funny that u mentioned Baltimore. We went there last Chol Hamoed, and thought it was the most fantastic trip, not to mention that if u are looing to make a 2 day trip it is a 45 min drive from Washington D.C. ( we didnt do D.C., but s/o we met in Baltimore mentioned it)
I found it fun for all ages, and “Kosher” enough for big boys.
We were told to leave a lot of time for the aquarium, and sure enough it is HUGE and really beautiful. We did book tickets online in advance which was great, we avoided lines. We satayed in a hotel no too far away so we can be close to Minyanim.