I don't know about Bethesda...but LOVE Samba! It is one of the trickier Latin dances (but my personal favorite) and requires A LOT of patience learning the rhythm. Most of my Zumba students get discouraged with this style...but I tell them, once you put in the time to get it down it is SO much fun!
Other places to check out Samba:
www.rodamovements.com/
http://www.meetup.com/brazilians-123/members/3585259/?op=&memberId=3585259
(Danielle Areco holds Samba lessons at various places all over the area and I hire her to do my Samba workshops)
www.dcdancecollective.com