I saw Marah a long time ago, opening for Steve Earle at the 9:30. I wasn't blown away by them then, but based on good word of mouth, I'd give them another chance sometime.
Once you get over the strip mall effect, Jammin Java is a great venue. I'm no sound expert, but I've thought it was very good, even during a full on rock show. The seating is a bonus, though they get rid of it during larger shows (and this one may be such). The food is reasonably tasty, and the staff are always nice.
Plus, I was told (by a fellow 9:30 boardie) that they let children under six in for free, unlike the Birchmere and Wolftrap, which charge full adult admission price for newborns and older.