I am going to need to travel to Arlington, VA (Ballston area) on
business fairly often. Does anyone have any tips on the best and
nearest general aviation airport to fly into

You'll probably want to go to Gaithersburg (where I fly) or Manassas. From what
my instructor told me, you would need to have written permission and a lot of
red tape to fly to National within the "free zone".

GAI is a little closer to a Metro subway stop if that makes any difference, and
Ballston is on the Metro (after a transfer from one line to another downtown).

Dave Sproul, Bethesda, MD