Although Scarlet Ranch had somewhat humble beginnings at 424 Broadway, the swingers’ club moved to much bigger digs in 2012: the former Northwoods Inn steakhouse in Littleton. The 18,000-square-foot log-cabin-like retreat bills itself as “a very diverse lifestyle club for ladies, select single men, and classy couples.” Scarlet Ranch, which attracts a clientele whose average age is 37, offers year-round cabanas, a tipi with custom lounges, and a fire pit.