After you complete Act three, enter the hotel, & go down the hallways until you reach the lounge with tables & chairs. There will be about ten bottles of alcohol on the bar that you can pick up. These bottles of alcohol will respawn one time you exit the hotel & re-enter the hotel, travelling the same way you went. Collect as lots of bottles of alcohol as desired, then go to Harland, & trade the bottles of alcohol for Molotov cocktails. You will get Molotov cocktail for every bottles of alcohol. Repeat this as lots of times as desired. A Molotov cocktail can kill most zombies in a single area instantly.