I'm not convinced the killer is shooting from hotel balconies/rooftops; I'm inclined to think the fact that many of the shooting locations are at major exits off major interestates means there will be an abundance of both gas stations and motels/hotels clustered around. But I think all options should be turned over and examined, so the rooftop sniping is as good a guess as a shooter-on-the-ground or shooter-in-the-van theory.
Georgia Ave. itself is a main street. East-West Highway (Rte. 410), a quarter of a mile north, is another main street. Nearest major highway is the Beltway, maybe three miles north on Georgia.