I WISH I could forget the first time I drank tequila. The shots I did in Cancún that spring break left me feeling dreadful enough to swear off any tequila that wasn't heavily disguised in a frozen margarita.

Yet 18 years later, I found myself in the town of Tequila, the booze-producing mecca of western Mexico. Just off the town's sun-dappled, cobblestoned main square lies the Mundo Cuervo factory, where hearts of agave, a desert succulent, are cooked, juiced and distilled into spirits for the world's largest tequila brand. While taking a guided tour, my husband and I came upon an exalted display of Jose Cuervo Especial (formerly known as Gold). I must have grimaced. "This will give you a bad hangover if you drink it alone," an employee acknowledged. No kidding.

But tequila isn't what it used to be. High-end versions (those made from 100% agave), comprised about half of U.S. imports last year, up from less than 2% in the 1980s. New artisanal brands, including ones from the likes of George Clooney and Justin Timberlake, are constantly hitting the market. Tequila is no longer just a frat-party drink, but a libation that deserves respect—and to be sipped like wine or whiskey.

Like those tipples, tequila has terroir—characteristics that reflect the soil, climate and other aspects of its place of origin. By law, true tequila can only be made in parts of five Mexican states; most of it is produced in or around Tequila, a city of about 60,000 in the state of Jalisco. My husband, beverage director for a tequila bar in Manhattan, convinced me to go on a weeklong bus tour of the region this summer, in pursuit of top tequilas. (Though he's in the spirits business, he does not work for any brand.)

In the highlands of Jalisco, blue-green fields of spiky agave plants blanket the hillsides around the centuries-dormant Volcán de Tequila. Distilleries of all styles—some traditional, some industrial—are scattered across the valley. As we made our way from one to the next, we sampled more than 40 different varieties of tequila, including a 110-proof blanco out of a cow horn (Tapatio) and the world's first certified kosher tequila (Casa Noble). We also tried our hand at harvesting agave, dined in a candlelit cave and sampled the best churros of our lives.