Some trendy new residential communities are rising around Clark County and they’re showing what one might call “moxie.”Offering gyms, movie theaters and even in-house hairstylists, the buildings are booking fast even though they aren’t open yet. Rents start in the low $1,000s and only go up from there.These are not downtown high-rises aimed at the millennial generation. They are senior living facilities.Demand for senior housing is growing as baby boomers enter their golden years. According to the U.S. Census Bureau, Clark County’s share of residents age 65 and older grew nearly 40 percent — by about 20,000 people — between 2010 and 2016. The demographic is growing faster than the overall population.Senior living facilities, while still dominated by older generations, are rising to gather new retirees. Industry experts say the newest buildings could be just the beginning as the aging population gets bigger. Meanwhile, cities are adjusting building codes and even offering incentives to developers to prepare for the shift.New buildings, new lifestyles“I was all by myself in a big house,” said Don Smith, 87. The Korean War veteran saw his neighbor’s air conditioning fail, holding comfort hostage for $12,000 in repairs.Smith, seeking a residence he didn’t have to maintain, signed a lease at The Lofts at Glenwood Place last month. There, residents live like apartment dwellers but with access to housekeeping. They can add a la carte services, such as meals or transportation.