Not sure if you want to travel this far afield, but I live in Northern Virginia near Dulles Airport (about 1 hr 15 min) from Baltimore. There are TWO great stores in the area:
Angela's Happy Stamper
http://www.ahappystamper.com/index.htm
Angela is wonderful and carries a great selection of stamps, paper, copic markers. They do awesome demos on Tuesdays at lunch and a free make-n-take on Thursdays.
Scrapbooks-Plus
www.scrapbooks-plus.com
If you're more into scrapbooking, this place has TONS of paper and embellishments.
Also, I've heard that somewhere up there in Maryland is an Offray ribbon factory outlet. Not sure exactly where and I've never been but I've heard great things.
Check out the websites or just pm me if you want more info. I can also tell you that downtown DC is gorgeous in April. The weather is usually good and sometimes you can catch the cherry blossoms in bloom (see my avatar!).
Have fun planning the trip!