Josephine Craytor followed a friend's advice and decided to move while she was young enough to make the decision for herself. She and her husband were one of the first residents of the Highlands at Pittsford, a retirement residence 12 miles east of Rochester, N.Y., that opened six years ago. The Craytors moved into a two-bedroom, two bathroom apartment and became active in developing programs for residents. One program is aimed at preventing falls. Specialists suggest taking the retirement housing search slowly. There are many different types of housing available today. There are about 2,100 continuing care communities across the nation, serving about 600,000 people. According to David Schless, much of the growth in senior house living will be of this type. The population in continuing-care communities has already surpassed that of assisted living projects, which boomed in the 1990s.