We've had a great time with the Adventurers this semester. My Shotgun Buddy and I are taking a group of ten kids on a field trip every week for our homeschool co-op. This year, I have Mxyl and Klenda as well as Choclo and Oob (and 6 other kids).
We started off with three weeks of the Air and Space Museum. Seriously, that's about how long it takes to do it thoroughly in two hour bites. We didn't even get to everything, but we hit the big stuff for our kids.
Next we did the Capitol Building - the older kids loved the inside, Choclo and Oob loved the duck pond. You can get (free) tickets here. The tours are one hour and very well done.
Then it was the Bonsai garden at the Arboretum. They were quite fascinated by the giant tiny trees.