Here's a link the the Washington Post's Going Out Guide for the Editor's Picks for current museum exhibits in D.C. and the surrounding area. Perhaps you can find something that interests you.

http://www.washingtonpost.com/gog/search/q,categories_Exhibits,datenavs_This%20Weekend,editorialreviews_Editors'%20Pick,searchType_facet,sortSpecifier_Date.html

If you like the Impressionists, you must put the National Gallery at the top of your list, it has many excellent and famous paintings in that style that you shouldn't miss. Note that "the Smithsonian" is a term that can cover all the museums along the mall and then some; go to this web site and browse around to see which of them might interest you most.
http://www.si.edu/Museums
Be sure to click on the Exhibitions link, too, for specifics.

If I were you, I'd spend the day on the Mall, checking out the museums and maybe walking to some of the monuments if weather and energy permit. Have fun!

Thanks! I'd meant to say that I've somewhat recently been to the National Gallery but it's been much much longer since the monuments or mall and Smithsonian museums ...

Renwick is a lovely gem.

Hi, Joe, well, in that case, you know how great the National Gallery is! It's one of my personal favorites.

Have you seen the MLK Jr. Memorial and the WWII Memorial? If the weather is OK and you like a nice long walk, those are definitely worth checking out. But you can never go wrong with any of the Smithsonian museums... have you seen the Museum of the American Indian?

There are some great pieces from the Impressionist period at the Smithsonian's American Art Museum in Penn Quarter. You could combine that with a trip to the Renwick & the Corcoran.

Oh, thanks for the tips. I had wanted to explore the PQ area anyway, as I've heard how nice that area is now.

Sounds great. I'm thinking Corcoran first, then Renwick, then walking across White House to end at Smithsonian American. A busy but fun day!

Update:

Did Renwick, walked to White House, then Smithsonian American and National Portrait Gallery. Had a yummy early dinner at Proof. Wanted to explore more of Penn Quarter but it was pouring and I came unprepared ...

Thanks for all the tips.