Lots of places to go, of course, but I'll give you a few of my favorites:
For lunch/Dinner, my wife and I love going to Guy Fieri's Vegas Kitchen & Bar. Fantastic food.
If you're looking for a good steak, I'd recommend "Cut" by Wolfgang Puck (in the Venetian). We've been to a lot of Steak/Seafood places in Vegas, and "Cut" has always been the best. My wife and I have even eaten there 2 nights out of a week stay since we like it so much.
I also always make a few trips during the day to the Pinball Hall of Fame while things are slow everywhere else. They are located a few miles off the main strip and have about 200 pinball machines and around 50 arcade machines. Lots of nostalgic fun for me, and relatively cheap.
The Carroll Shelby Museum is a must, I always make a stop there while in Vegas. It's not nearly as good as the Shelby American Collection in Boulder, but it's good.
There are lots of exotic car rental places out there also, last we were out there my wife rented me a Ferrari 458 for a half day cruise through the Red Rock Canyons. Not sure how much it cost (couldn't have been cheap) but it was super fun and beat losing the money at the tables.
I always go to Exotics Racing at the Speedway to at least watch the cars on track.. with any luck, they'll be flying out of Nellis AFB across the road too..
I'm going for a conference. Thought about going to the fight but I'm not paying big bucks to see it - and I don't care to spend the effort to sit in the nosebleeds, either....so I'll probably just bet on it and watch it in the casino.
Def going to check out the Shelby Museum.
Thanks for the suggestions. We are foodies so will try to get to these!
The auto collections display on the 5th floor of the Linq's parking garage is pretty neat. A lot of nice classic and modern cars on display. Last time I went they had a few '67 GT350's on display. They even had one of the GT500 Elanor clones that was built for the Gone in 60 seconds movie.
Shelby America is awesome, lots of great historic cars. Exotics racing is a must do if you have any interest in driving other peoples Porsche Turbos, Ferrari, Audi R8, Lamborghini... around a race track. The food available is amazing, gambling is nice, I believe I've heard they opened a strip club...not sure what goes on there. If you're near a big sports book, I believe under 9 rounds is nearly even money. Likely a good bet!