as regards San Gimignano, there are plenty of vineyards all around San Gimignano. You can ask for a visit at a tourist office, or even at a farm itself. I think you'll find friendly people and a proper organization

If you are a wine expert, you'll know that the typical product of San Gimignano is the so called Vernaccia (a peculiarity of this place). That is different from the Chianti D.O.C.G. wine.

If you want to see a vineyard merely because you like this sector of agriculture, well, you can turn round yourself. Wherever you see there will be the chance to visit a vineyard.

Remember: San Gimignano is at the beginning of the Chianti Classico hills (the famous Chianti Gallo Nero), and very near one of the widest cypress-woods in Europe.

Andrea in Poggibonsi