Las Vegas is supposed to be "Sin City" but in reality there aren't many things you can do in Vegas that you can't do elsewhere around the country. Drugs and prostitution are still illegal. There are strip clubs, but the rules are surprisingly strict. Gambling is becoming more common all over the place. Everywhere has drinking, just in Vegas you can do it 24 hours a day and on the street.
One thing that might be somewhat unique to Las Vegas in this country is topless sunbathing. A lot of the hotels have a separate "European" pool where guests must be 21 to enter, and most of the time charge a fee for males. Most of the females at these pools stay covered, but prefer to be there because there are no children running around.
A recent story by KLAS outlined a list of rules sent out by Clark County to all of the major resorts. You can read the letter here (PDF). Among other things Clark County code outlaws "best swim suit", "best chest", "wet t-shirt" and "booty shaking" contests and parties at topless pools.
Clark County Commissioner Steve Sisolak was quoted as saying, "There is certain behavior that's acceptable. There's certain behavior that's not acceptable… (Lewd behavior) will absolutely, 100 percent not be tolerated. That's not what this is about. It's not a party atmosphere."
I understand that the county doesn't want drugs and prostitution at these pools, but I'm not sure I understand the logic behind banning some of this stuff. You can't have a best swimsuit contest at a Las Vegas pool? Wet t-shirt contests aren't allowed in "Sin City?" With visitor numbers struggling as it is, I don't think limiting fun is a good idea.
Read more about the new pool rules at KLAS.