Niten Ichi is fairly rare, if I'm not mistaken. I'll let one of the Niten guys answer the where bit.
The general advice for people looking for a dojo is to figure out what is available in your area and choose from that list. Qualified instruction in genuine Japanese koryu is hard to find. Unless you are willing to relocate out of state, or possibly cross country, you may not be able to find what you are looking for anywhere nearby.
I know for a fact there is a highly trained Muso Jikiden Eishin Ryu instructor in the DC area, but that's the closest I can get you. There should be other styles a little closer to home.
Charles Mahan
Iaido - Breaking down bad habits,
and building new ones.