There are a lot of things to do here! It all depends on what you want to do. Some have already mentioned them.
Shopping:
Fashion Show Mall (on the strip right next to where u r staying Treasure Island/T.I)
2 CCO's- One at the Premium Outlet (Outdoor Mall) (Charleston & Grand Central Rd) & the other one is at the border of Nevada and California. (Forgot where ur coming from but if ur from Cali you will pass it if driving.)
Venetian Hotel- they have a shopping area in there (w/ Sephora
Guess, Kenneth Cole, Aldo, Brookstone etc.)
Caesars Palace Forum Shops- almost the same stuff as the Venetian but more pricey. This is where the MAC Pro store is.
Town Square- Its an outdoor mall, reminds me of California
there's VS, Sephora, MAC, Apple store, Abercrombie, Old Navy, movie theatre....
Clubbing:
-Hottest club right now is XS at Encore. Its kinda hard to get in b/c the lines are so long unless u know someone who can cut u thru the line
- The Bank at the Bellagio
- Body English at the Hard Rock (don't really like this place...too dark, small, & don't really like the crowd there....)
- Pure at Caesars Palace
Those were just some of the things I could think of at the top of my head...
But check out vegas.com that might help. Sometimes they have deals on the site too. Good luck!!
P.S. I know you said you were coming in Aug. but the weather right now is about 112 degrees F. So please be prepared for the heat and drink lots of water and sunscreen when outdoors!! (A hat and sunglasses too!) lol