The Desert National Wildlife Refuge Complex consists of four related areas within two hours of LV. The Moapa Valley NWR is not currently open to the public. You can see information about the other three below.
Hedgehog Cactus - Corn Creek Field Station
Cathedral Gorge features eroded hills full of cave-like branching slots. Fun to explore; rewarding to try to photograph from inside. The Nevada state park has a pleasant campground with amenities that include hot showers. About 2.75 hours from Las Vegas.
Michael Heizer's 1969-70 land art piece Double Negative is cut into the edge of Mormon Mesa overlooking the scenic Virgin River valley. Hard to photograph, I found it to be an "interactive" piece that one needs to walk around, climb down into, view at both sunrise and sunset, etc. to appreciate its variations, scale, and bravado. Tried to see Heizer's even more monumental City, also in the region, but Heizer has deliberately made it inaccessible, pending completion, with a gated road and obscuring berms.
Buffington Pockets shares the features of Valley of Fire: twisted red rocks and ancient petroglyths. Valley of Fire is a state park accessible by car while Buffington Pockets is a power toy playground requiring 4WD, so check out Valley of Fire, first. If you are in the Buffington area (Moapa Valley), check out the Moapa Valley National Wildlife Refuge, a warm springs oasis home to the endangered Moapa Dace.
Great Unconformity Interpretive Site is marked by an unimproved dirt parking lot along the south side of E. Lake Mead Blvd (NV 147). The path is badly littered, the interpretative geology signs are vandalized, and the smog makes for challenging photography, but maybe worth the 1/4 mi. hike up for the view if you're heading east early in the morning.
Las Vegas from Fenchman Mountain
The mouth of Grapevine Canyon, a dirt road drive from the highway and a short hike in, contains the densest petroglyth panels I have seen.
Petroglyths at Grapevine Canyon
Desert National Wildlife Refuge is located in the Mojave north of LV, with three 4WD access points off Highways 93 and 95. Visitors are on their own and should be well researched and equipped for the backcountry. This year's forays were scouting trips for future expeditions.
Recovering Yucca Forest - Mormon Well Road
Pahranagat National Wildlife Refuge is an oasis of lakes along Highway 93 about 80 miles north of LV. Birding, camping, and native rock art are its principal offerings, but it also contains a 4WD access into the Desert National Wildlife Refuge. Check with the office before using the 4WD roads, as some are no longer passable.
The "Dunes" are more like badlands and the "Recreation Area" is a power toy playground.
Power Toy Tracks
Red Rock Canyon National Conservation Area is <1 hr. outside of Las Vegas. It features a scenic loop drive and hikes of various lengths and challenges.
View Coming Out of Icebox Canyon