Bring a sweater. One of the things that makes Napa such a great place to grow grapes for wine is its extreme shifts in temperature, meaning a 90-degree day can sink to a cool 50 when the sun goes down. Be sure to bring warm clothing if you’re going to be outside in the evening. Take Silverado Trail instead of Highway 29. It’s usually less crowded and more scenic. Don’t drink and drive. A good rule anywhere, anytime, but especially in Napa Valley, where drinking is common and cops are vigilant. Sit at the bar. Most restaurants offer a separate bar menu, which has more affordable, casual offerings like steak frites or burgers—and you’ll probably get some good insider tips while you’re at it.