Your vacation is a time to relax and a wine tour fits the bill wonderfully. But my tour guests are often surprised by how tired they are at the end of a day of touring. Often dinner plans are scrapped and wake-up calls ignored. Although they are thoroughly relaxed at the end of the day, they are not up for much more. And this not just due to inebriation—though excessive amounts of wine can figure in. Abiding by some good rules of thumb will help you maximize your energy without overdoing it.