Hellobee Boards

The Lee District Rec Center park is pretty awesome (playground and splash park in one space), but I know it books up pretty far in advance. I spent hours scouring playgrounds for my kiddo's June 1st birthday party and unless I'd planned it months in advance, pretty much everything was booked. Doesn't hurt to look though. Fairfax county's Parks website has a searchable site where you can look for shelters and picnics and such and they'll show you availability as well. Same for Arlington county. In Alexandria I think you have to be a resident to rent one of their spaces.

i haven't been there in a while, but really liked meadow lane park in vienna. large playground, good shade, a pavilion and restrooms.

You can rent pavilions/rooms at Frying pan farm or a pavilion at clemajontry or however it's spelled (in McLean) - I've had NoVa friends hosts parties at both and they were both a blast!

@abmamma: Honestly, we've been to birthday parties that were just at a playground without a pavilion (ex. blue park next to King St metro) and the parents just set up a table with the cake and snacks/drinks and just let the kids have fun at the playground. At one party the parents of the birthday child brought squirt guns but I don't even think that was necessary and the kids all had a great time. When it was time for cake, we just sat on the ground. So, don't despair if you can't necessarily find something to book...but I'm also on team casual/no fuss birthday party!

@abmamma: Ooh, another idea: Burke Lake Park. The train is fun for littles.