No one under 21 can play in a casino in Nevada (and most other places in the country, for that matter; some jurisdictions allow under-21s to play).
People under 21 can pass through Las Vegas casinos, but the operative word here is through. Anyone under 21, including older kids on their own and younger kids with their parents, must be moving along toward some non-casino destination, such as the elevators to the rooms, a restaurant, a showroom, the pool, the arcade, anywhere but the gambling floor.
If you're with your 16-year-old son and stop somewhere in the casino for some reason, you can expect a security guard to approach you pretty quickly and invite you to be on your way. The guard might tell you that both you and the casino can be fined for having a minor in a gambling area (this is so rare that you could argue the point, but it's not recommended that you get into a tussle with a casino security guard).
You and your son can stop in a casino area only if, for example, you're standing in a line to see a show or enter a restaurant or buffet that winds through the joint.
That's the whole story. We've never heard of any tours through a casino in Vegas -- mainly because they all look the same: thousands of slot machines and scores of table games in the big ones; hundreds of slots and a dozen or two table games in the smaller ones. Some have only a few slots and no table games. As long as you keep moving, you can see every casino in Las Vegas. But we predict that once you've seen two or three of the big ones on the Strip, you'll feel like you've seen them all.
You catch the table action in the center of the casino. Out from there are all the slot and video poker machines. Fine. But the sights and amenities that differentiate one casino from another -- the hotel lobbies, restaurants, food courts, bars, lounges, showrooms, malls and shops, pools, arcades, museums and conservatories, themed architecture, and the like -- are all on the perimeter of the gambling floor. That's where you should focus your attention with a 16-year-old: walking the inside walls of the buildings.
