Nevada is a defacto open carry state and you may open carry if you choose. If you open carry in the high traffic tourist areas of Las Vegas you may have a visit from Metro or, Casino personel may/will ask you to leave the property if you open carry in any casino. If anyone in authority in any private establishment asks you to leave you must leave under Nevada's trespass law.
There is no restriction on having a firearm in your car, open or concealed as long as it is not concealed on your person (unless you have a permit).
See the thread on concealed carry for more info:http://glocktalk.com/forums/showthread.php?t=881163
Places that you may not carry any firearm include those so indicated in federal law, including the Post Office. It is unclear that you can or cannot open carry at the locations that are restriced, by law, for concealed carry. Do you want to be the test case?