For Dinners: here's my reccommendations.
Mama Ayesha's.
Zaytinya (for fancier dinner)
Smoke N Barrel has Vegan BBQ. no shit.
Indique (indian)
Cheap Eats:
Amsterdam Falafel
Julia's Empanadas
Radius Pizza
Founding Farmers
You can view the entire list here.
http://www.vegdc.com/restaurants.phpFor Kickball check out DC Freedom on the mall, or DC Liberty or DCKickball Thursday (where you'll see some of Rockstar) up in Adams Morgan. All three has enough shenanigans for your thursday.
For music, check out The Black Cat. Great indie venue! And the Vegas Lounge has a sweet soul band playing occasionally.
As for museums, Air & Space, American History, & the Native American are the best. (and free) There's also Crime & Punishment & Spy Museum (though they are not free)
WWII, Washington & Lincoln Monuments are close to each other. (and kickball play near them) You can also see Teddy, MLK Jr, and the Vietnam and Korea War memorials. which are cool.
If you have a car, go see Thom Jefferson.
Best local dive bars are The Blaguard, Kelly's Irish Times, Chief Ike's, & the Red Derby.
Shoot me an email when you'll be in town, i'll be able to give you more in depth. Plus i play ball thursday so you're more than welcome to come out with us.