I go to Vegas once every 45 days or so, so I have a good idea where to go if you are single.
When are you going exactly? If you are going during the pool season, then that is where you will want to make contacts. Hang out at the hotel pool (or go to a hotel with a pool party like at MGM, Encore, or the Cosmo).....and mingle mingle mingle. Meet guys too just so you don't look like you are there by yourself. But the key is to talk to as many girls as you can, get their digits, and then later that night text them and see which ones are down for meeting up at a club, bar, whatever when they are drinking and even more likely to want to hook up.
As for where to go at night? If you want the older cougar types, hang around the bars at Ceasers Palace or some of the older casinos. Especially the casino bars. If you want younger? I would rec any of the clubs like XS, Surrendur, Marquee etc. I HIGHLY HIGHLY rec Light at Mandalay Bay. My fiance and I went last weekend, and I was blown away by it. I usually like the clubs with the outdoor areas as well as indoor like XS or Surrendur, but Light, while being an all inside club, was great. It's pretty much a Cirque Du Solei show along with a club. Great lighting, lasers, Cirque people putting on shows, great djs, and the girls were spectacular. If I was single I would have been all over it. TONS of hot girls dancing away. I think another really good club with lots of sloots is 1 Oak at the Mirage. IF you can't score there, you can't anywhere. If you like Asians I would rec either Light, XS, or Surrendur.
The key is to just go and talk to as many people as you can. Everyone is just like you, on vacation, not knowing anyone else there besides who they are with, and most have a sense of freedom and adventure that only Vegas can give you. In other words most are down to meeting new people and doing something out of the norm. So just go in with a F it attitude and have fun!
Good luck.