I guess it really depends on where you are staying and what type of transportation you will have. KGAI, Montgomery Airpark in Gaithersburg, MD is a short ride away from the Shady Grove Metro station. It is located North of DC. There are two flight schools there, one is Light Sport, Fleming Aviation. They have three Piper Sports and a Carbon Cub.
There are 5 RV's based plus one under construction at the field. Also a good restaurant with a deck overlooking the runway.
If you decide to come here, give me a shout out and we'll meet up. I'll be happy to take you up on an aerial tour.
http://www.learntoflydc.com
http://www.flemingaviation.com/tiki-index.php