welcome to Vegas. do a search on the boards here for vegas trails, or vegas valley. there is a lot to do out here.
and just so you know, it is illegal to actually wheel inside the Valley itself, due to dust concerns, ar at least that's the excuse they give. (you can go Nellis Dunes however and play out there....it's out by the Air Force Base...go wheelin' and watch your USAF planes kick some A).
there are several groups here to look at
if you like the easier stuff/ trails that go somewhere, scenery, Nevada backroaders. this is the club to which I belong, and there's usually always someone able to go out with you. Always willing and able to help you out in a stuck. Biggest club in the state.
if you have a money tree, like the harder stuff and think breaking your crap everytime you go wheeling is one of the simple pleasures of life, Total Karnage.
if you like a mixture of the two, Vegas Valley 4 Wheelers......all have websites www.vv4w.org
Vegas Valley is more of the harder core/ rockcrawling group (TK just goes out to beat their rigs cuz they can), but they appreciate the scenic stuff, too. there are a lot of members that belong to all 3.
there's another one called Jeep Thrills that's setup via the meetup.com website...yeah, avoid them. their reputation is not the best.
is a board to get on too.