At 7 the thing they like best is the hotel pool. I’d do Baltimore so you can add the aquarium. Or Williamsburg. But definitely make sure there’s an indoor pool.
+1 for NYC. I took my daughter when she was 7 and we had a blast: saw Frozen on Broadway, went to all the tourist traps (M&M store, Dylans Candy Bar), ate at Ellen's Stardust Diner, which is super touristy but also super fun. The train up and back are easy and part of the adventure.
Baltimore - aquarium, science center, art museums, baseball, history (e.g., tall ships, Ft. McHenry), zoo, nice parks with playgrounds like Patterson Park, lots of food and shopping options
Ocean City or other Eastern Shore beach - walk on the beach, swim in hotel's indoor pool
Any ideas for a mother/daughter weekend trip in the Spring? Ideally somewhere that is close-ish to DC. My daughter is 7.
Best I could think of is Philadelphia, but I'm sure there are other options that would provide a few fun activities for my kid.
I'm not really outdoorsy.