The tequila here is top notch -- so don't be wary about the low prices. Even much of the less expensive stuff is still high-quality.
Things are happening in Guadalajara. It's home to the country's top book fair and is the first city in Mexico to get an IKEA. But the local culture is what you're really after -- spend your time in the Lafayette section of the city to experience some of its top bookstores, galleries, bars and cafes.