Here is some invaluable advice. Book a limo (or two) for transport from the airport to the hotel. Standing in the cab line at the airport on arrival sucks wind. Or rent a car/van. No matter how you get from the airport to your hotel, pack light and only do carry-on. Buy a bottle of Febreeze and bring less shirts or pants/shorts. Bring a pair of slacks and closed-toe shoes. Some places have dress codes, plus it's Vegas! You want to be able to look classy when you can.
If you take a cab to or from the airport, beware that Vegas cabbies are notorious for squeezing every last cent they can out of you. They will longhaul you at every chance. To/from the airport, this phrase is your friend; "Take Paradise, no tunnel". They'll try to get you to take the freeway because it's "faster". Baloney, it's a longer drive and therefore more expensive. Just burn that phrase into your skull and never forget it.
Watch out for any suggestions cabbies make too. Most places (clubs, strip and otherwise) pay the cabbies kickbacks. So the cabbie suggests a place to go and they charge you a big entrance fee, with most of it going to the cab driver.
For such a long trip, the casinos and bars are going to get old after a couple of days. Look into a show like Blue Man Group. I haven't seen it there, but I have been to the Chicago production six times and it's awesome. Golf is an option, as are daytrips to the canyon and Hoover Dam. Break it up though. Get sleep, even if it's just a few hours a night. Some people go and try to stay up the whole time, that's just dumb. Drink lots of water. I'd suggest at least one glass for every cocktail you have. It's very dry. Bring a jacket, it gets cold there at night.