Hi, My family will be in DC for 1 day. We have dinner reservations at 6:30p that night so we have until we get out of hotel in the morning(9a-ish) till about 5p to go to the zoo then walk around the mall ( no museums, just see monuments ). Is this doable or too much for one day? Also we will take the metro to travel between.
That is very doable. The museums around the Mall are free, so if you need a bathroom or just want to take a break from the heat, you can pop in a museum, see a few things, and leave. The Natural history museum has the Hope Diamond and dinosaur bones; American History has a great First Ladies exhibit, and the Air and Space museum is just fun in my opinion.