This has been my favorite bar from our Vegas trip! I have visited daily at the locations in Harrah's and Caesar's Palace where both of my bartenders have been awesome!
They let you taste the frozen drinks pre-alcohol before you decide which one you want. I've tried a few different ones now but always come back to Purple Haze with a double shot. They also have a variety of sizes to choose from, a few of which are souvenir cups! My favorite part is that if you come back with your receipt, your refill is $2-3 cheaper than your original order!