In order of their proximity to Las Vegas:
Red Rock Canyon, 20 minutes out on NV 159, desert canyonland and sandstone scenery, featuring the 13-Mile Loop that you can drive or bike, stopping at the scenic vantage points along the way. www.redrockcanyononlv.org
Boulder City, 35 minutes on US 93, small town full of character and history, www.bouldercity.com
Hoover Dam, 45 minutes, one of the seven architectural wonders of the world, tours and views, www.usbr.gov/lc/hooverdam
Lake Mead, 45 minutes (to start), largest National Recreation Area in the Lower 48, beaches, marinas, and boat cruises, www.nps.gov/lame
Valley of Fire State Park, 60 minutes, much more spectacular and extensive than Red Rock, though 40 minutes farther out, www.parks.nv.gov/vf.htm
Mount Charleston, 60 minutes north on US 95 to NV 157, beautiful climb into rugged Spring Mountains, cooler, wetter, and fresher, www.mtcharlestonlodge.com