Ciao NJ Wine Lover and welcome to the Forum!
If you're just looking for a short half day wine tour from Siena then we'd recommend staying pretty close to the area. Since you're already going to the Montalcino area for Brunello, you might consider a tour centered around the other big red wine in the area, the Vino Nobile di Montepulciano.
Or how about trying out a tour around the Vernaccia di San Gimignano, a white wine made in the area surrounding San Gimignano?
As for specific recommendations, we suggest taking a look at the tours offered here:
http://www.partner.viator.com/en/835...in-Tuscany/ttd
While many start in Florence (most popular), I am sure there might be a possibility to start the tour from Siena.
Hope this information is useful in your planning!![]()
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