I'm not a resident but a repeat visitor, does that count?
We just went back in April, and we had a good time.
Few tips:
The Metro is amazing, and can get you where you need to go very easily. If you get a hotel near on on a Metro stop, you've got it really easy! (Just down the escalator you go!)
Washington Monument tickets go away quickly. You get timed tickets, and they are first come first serve. There are NO BATHROOMS in the Washington Monument! The closest one is a porta potty on the rear area, and the castle if you can hustle across the mall! (porta potty lines are long)
The American History museum is very nice. Be sure to explore all three floors!
The Natural History museum is very neat too, although there are some dated dioramas in there. There is a neat baseball exhibit there that opened up when I was there early April (yes, what is baseball doing in Natural History? Didn't make sense!). That was very informative.
The Air and Space Museum is good if you like that sort of stuff. There is a new Air and Space musuem in Virginia, but we haven't gone there.
The Hirshorn has some interest popular art if you like that.
The African Museum is very very peaceful.
There is also a very cool sculpture garden near there as well.
The Castle had a very interesting Salvador Dali exhibit back in April.
DO NOT stand up during the changing of the guard in Arlington Cemetary. YOU WILL GET YELLED AT! Arlington Cemetary is a long walk from the entrance to the JFK stone.
National Zoo is a lot of fun. Get there early to see some very active animals. From the Woodley Park metro stop, it is a bit of a hike (uphill), but going back is a breeze!
There is a bag search in every Smithsonian. The lines were really long later in the day. If you got there around opening time (I think it waS 10) it wasn't too bad.