The National Cherry Blossom Festival continues through April 12. There are activities to participate in or just go downtown to take in the beauty and visit a few museums. You can pack a picnic lunch and enjoy it on the National Mall.
http://nationalcherryblossomfestival.org/cms/index.php?id=390
With many kids out of school for Spring Break, this is a fun day trip. Just be sure to get approval from your host parents first. Enjoy!