Yeah, i don't really know any around the MD area, i mostly just shop online. I know when i was a kid there was a store in Baltimore, but its been awhile and i don't remember the name... :-/
I've been to all 3, and would say Denny's shop is my favorite. Packed with books, and Denny is the real deal. A guy that's made his living performing with some of the biggest names in magic, and is one of the most respected performers in magic as well. He'll tell you what works, what doesn't, and sell you some of the best magic ever. A true class act in my book!
Best.
Steve
P.S. Whereabouts are you? Check out www.magi-whirl.org and look into going...it's the best convention in the area, and with Paul Green and Jeff Mcbride lecturing this year, it's sure to be awesome!!