Agreed, having been to there, the Dabney, and Tail Up Goat relatively recently, R&O was the best food of the three (though all were great).

For tennis there really isn't an option to go to courts where people will be hanging out and inviting people there to join. Most courts are super busy so those kinds of things need to be planned in advance.

That said, this facebook group is reasonably active and I know people regularly find other people to hit with through it: https://www.facebook.com/groups/dmvtennis