Skip your hotel gift shop and go here instead...it's convenient and you'll save a few bucks. Yes, it's a little more costly than your Walgreens back home but it's great for bottled water, booze, items you forgot to pack, and whatnot...they also have a good selection of Las Vegas souvenirs. I got a pretty decent shot glass for $2 and it was better than the cheap ones on Freemont Street and looked like the $4 ones sold in the hotel stores.
This is your go-to place if you are passing by or staying at any of the hotels in the area.