It sounds like a very fun project! And I second Hop's suggestion of having some fair trade teas. Fair Trade is a huge pet project among the more affluent and/or college educated in the Midwest.
I live in Indiana, and Victorian-themed tea rooms are quite popular among the ladies--particularly those who hang with church social groups. It seems that about once a month, a church social group will go to one of these tea rooms...so that's anywhere between 20-40 ladies at once. Naturally, they go to places that can handle all the people. I live in a pretty church-heavy area, so I get the impression that these groups basically are the bread and butter of this particular industry. That and bridal/baby showers.
If Maryland is somewhat similar, I would suggest looking into ways to ensuring you could handle at least 30 people at any one time. Then again, I'm not a professional business consultant or anything, so you might want to take what I say with a grain of salt.
Oh, and apparently Victorian-styled tea cups and saucers can get fairly expensive. One place in Indy sort of solved that problem by buying up all sorts of cheap, incomplete sets from eBay and estate sales. They have all the cups and saucers displayed along a wall on shallow shelves, and patrons can choose their favorites. It's a very popular feature for them and has the bonus of doubling as Victorian, tea-themed art.