Each vineyard is generally a tiny parcel of land in Burgundy. So most of them are unmanned. That's why there are so many. Larger domaines or chateaux usually have a sign up inviting passing tourists or wine shoppers to stop in. There are special roads designated as wine routes where you'll find plenty of places to stop in at. Also there are co-ops where a bunch of smaller growers team up to produce and bottle, or box, the wine. And you can taste there all day.

But if you have a specific domaine that you want to visit, yes you should call to make an appointment. Remember that people generally take off from 12-2 for lunch.

Oh, here is another good shopping place to stop by at Nuit-Saint-Georges. http://www.imaginarium-bourgogne.com/index.php?lg=en as they have expert assistants to answer any questions.