If someone orders a vodka tonic, don't you dare automatically pour him a top shelf brand. Use the well liquor in the speed bar that your establishment has designated for all non-specified drink requests. The difference in price can be significant and can make someone beyond irate. That being said, a few dollars more per drink can be good profit and good for your tips. You can feel comfortable suggesting or offering a better or higher priced alcohol than the well. For example, "If you haven't tried Tito's Vodka yet it's amazing. Want to try it?" Or "I'd love for you to try Tito's Vodka in your drink." Giving your customer the option of how their drink is made is most important.