There is also a Walgreens Drug Store on the Las Vegas Strip. Approximately 400 feet north of the MGM Grand on the same side of The Strip you will find a free standing Walgreens. They can be a bit pricier than the ABC store for some things, but are a little closer.
If you find yourself on the far north end of The Strip and in need of emergency sundries, The Riviera has multiple ABC Stores inside, but the main one in the lobby is 24 hrs.