We have already bought 2 houses with Mark's assistance, we are thinking about another purchase in the area, and we would not even think about working with anyone else.
He loves what he does, he truly likes working with people, and boy is he knowledgable, just lightly skin his book about reals estate in Northern Virginia and you will enough information to chose an area and a community that fits your needs, your personality, and of course your budget. Sorry I forget the link to the book, just ask Mark and he'll tell you.
Mark was open, honest, helpful, and was a bit of fun over a beer too.... Highly recommended!!