Westjet and Expedia have good flight prices (subscribe to Westjet's newsletter for last minute cheap flights). Print you boarding pass off the night before, and get the window seat (which goes to the wife). Wear pants that don't require a belt, and slip on shoes, to help with security. Bring headphones to watch the in-flight TV (Westjet). Always take the shuttles from the airport to your hotel ($6/person), as the cab ride can average from $30 (from airport) to $12 (to airport). Eat before you catch your flight home, as everything closes in the airport after 6pm. Duty free booze is cheap! Wash your passports (half serious -- we accidentally did this and every border guard had a chuckle and no one hassled us).
BRING COMFORTABLE, WORN-IN SHOES. Buy your own booze from a liquor store (ABC in the Miracle Mile shops is good). You must show ID when using Visa (which people use for everything, including buying gum). Text message instead of using your phone; it is way cheaper. Bring 1 more T-shirt and 1 less pair of pants than you think.
The Rio buffet is overrated; the Planet Hollywood and Paris buffets are better. The creperie at the Paris is cheap and filling. Le Burger Brasserie in the Paris has the best burgers.
The monorail is fast and not crowded, but is expensive and still requires significant walking. Take the Deuce (the double decker bus that runs from the strip to downtown), if you don't mind waiting and crowds. You pay cash ($2/ride, $5 for a 24 hour pass) at the front of the bus, and get a card you can swipe like a credit card. To get to the Vegas Premium Outlets, take the Deuce North, get off at St. Louis street, stand in front of the Denny's, and catch the 108 North to the Premium Outlets; the bus driver will announce it.
Cheap (1/2/5/10 cent) slots are fun. Find where the waitresses are walking around, sit down, flag them down and ask for beer, and tip them $1 (you can do this all night, if you want). Most casinos have poker tournaments, but I like the MGM and Planet Hollywood ($60 buyin) the best. The Caesar one was a joke (8 players?!?) Remember, play tight poker and you should come out ahead. The cheapest Blackjack I saw was at Slots-A-Fun ($2).
I've seen Ka (fantastic) and Penn & Teller (awesome). Check out the cheap day-of ticket booths (e.g., Fashion Show Mall). The Belagio water show is cool. Fremont street is a bit scruffier, and the light show is goofy, but the outside street party feel is cool. Fremont street has cheap booze & food.
We usually have a late flight home (they are cheaper). This time, we checked out in the express checkout box, but kept our card keys and hung out at the pool for several hours. Going to a restaurant or cafe and reading kills time also. My sister went to the MGM and watched TV pilots on her final day.
Vegas looked like the borg rebuilding a damaged part of the ship. I think Vegas is in for a hard landing. One dealer said she's never seen Vegas this dead in 20 years. The amount of new hotel rooms / timeshares / condos coming on the market in the next year or so is staggering.