Nevada is an open carry state because there are no state laws that prohibits open carry.
That said, no open carry on school grounds and in government buildings.
Also, unless you want an encounter with LVMPD, do not open carry where the tourists are at in Las Vegas (ie. the strip, casinos, Fremont St, the malls, etc.). Even though it is legal, it is strongly recommended that you do not. Remember that many tourists in Las Vegas are from countries that do not allow the legal ownership of firearms, so they will call the cops on you.
Check out the NV forum at opencarry.org
for more open carry stuff in NV.
If you want to legally carry a handgun almost anywhere in NV, get a CCW permit.
NV is a shall issue state and they do issue non-resident CCW permits.