Great Falls Park in VA, they can crawl on the rocks. Go to Mookies BBQ or Pietanzza after.

Give a list of ideas to the parents and have them pick. This is not completely your job OP. It's nice of you to help out, but it's not up to you to make sure their kids aren't bored! I wouldn't visit a childless friend and expect them to entertain MY kids all day for two days.

Anonymous wrote:Kids are not mine and are from out of town. 5 and 3 YO. I had planned on the Potomac pirate ship or water taxi to National Harbor but neither work timewise with the little one’s nap at 1 pm. What do I do with them?

Duck tape and Velcro.

Go the nearest elementary school and play on the playground. They're fenced in, fun, close by, and open to the public during non-school hours.

Nature centers are fun too. There ubiquitous around here (and also have playgrounds).

Rec centers have indoor pools (some more fun that others).

Udvar Hazy

Two brand new boxes of tissues, gift wrapped. Curtosy of Ramona

When my kids were little we literally spent most our day at Turtle Park. Take a picnic lunch let them run around a nearby park almost all day. In the late afternoon, bring them home pop a movie in and let them veg.