Drinks - Everyone knows that waitresses bring you free drinks while you're gambling, however what some don't know apparently is that how often and how accurate your order comes seems to have a direct correlation to how well you tip your waitress. Naturally the stance of most casinos is that Scrooges should get the same service as normal people, but money talks. Don't listen to the blogs and posts that say $1 every other drink! They are wrong and I'm not sure where they got that number. Average is $1/ drink. Stick to that and you'll likely get stellar service.

Rooms - Only for high rollers. Get to know the pit bosses (easy to do if you're throwing out hundreds every hand) and they'll soon be comping rooms, giving you show tickets, and inviting you to come back if you hand out your contact info or sign up for a rewards card.

Gambling - Most casinos now have a rewards program of one sort or another where you sign up for a card and can then use that to gamble. Meeting certain criteria results in free "spins" on slot machines in most cases.

Shows - There is all kinds of free entertainment in Las Vegas, shows are anything with a performance involved. Here are some of the more fascinating free shows in Las Vegas.

Circus acts at Circus Circus performed daily.
Sunset Stampede at Sam's Town about 10-15 minutes off the Strip chronicles the pioneer experience.
Streetmosphere at the Grand Canal Shoppes in the Venetian is comprised of a variety of acts put on by performers from around the world.

Sirens of TI is a really cool show right on the corner of Spring Mountain and Twain with athletic pirates and stunning sirens.
Caesars Palace Statues are just statues until the lights go down and they come to life.
Masquerade Show in the Sky is at the Rio, it's a colorful act with high-flying performers.
The Fremont Street Experience with Viva Vision, Viva Vision is a canopy of lights stretching 1,500 feet and showing nightly, and throughout Fremont Street are a number of performers with 2 stages for free concerts playing almost nightly.

Free Sights - This is anything cool you can go see for free that is not a performance.

The Bellagio Dancing Waters is perhaps the most popular, it features jets of water that blast off in time to different music. Also within the Bellagio are the Bellagio Gardens, some of the most impressive horticulture in the world.The Mirage Volcano two casinos down has real fire and erupts every half hour after dark.
MGM has a lion exhibit just inside the front entrance.
The Venetian has a beautiful painted ceiling and an indoor canal, both popular with tourists.
On a clear night you can see the Luxor Light from miles around. Rumor is you can see it from space... we're pretty sure that's false but it makes a good story.
If you don't have a ticket to Paris, don't worry because Vegas has its own Eiffel Tower right on the Strip. Not quite as impressive but pretty cool none-the-less.
Go downtown to the Golden Nugget and check out the single largest real gold nugget ever discovered.
There is a Wildlife Habitat at the Flamingo. Naturally it features flamingos along with other wildlife.
You'll see many tourists stopping by the famous "Welcome to Fabulous Las Vegas" sign a bit south of Mandalay Bay on Las Vegas Blvd.
If you like fish you can pay to see the largest Aquarium in Nevada at Mandalay Bay, or you can see the smaller free one and Silverton, it's really cool and free.