Attendees of Londance Studios' lessons have seen some of the instructors before, and not just on the studio's brightly lit hardwood floors or in the mirrors that line the walls. Instructor Shirley Ballas lit up TV screens on Dancing with the Stars, and Tony Meredith did the same on So You Think You Can Dance. For more than 25 years, seasoned performers such as Shirley and Tony have spread the joy of kinetic expression at Londance. Two or three classes are held each day, in styles as varied as ballroom, salsa, and swing. Weekly studio parties enable dancers to show off their moves or scrutinize the mirrors to catch any vampires brushing up on the waltz they originally learned in 1790s Vienna.