Hi Dave
Montepulciano is the archetypal hilltop town... so your calves will be tested by the moderately short, but rather steep slopes. One of the rare places where tasting rooms / cellar doors operate like in Australia. Whilst drop-in is the norm, worth booking one or two visits as the hospitality is that much better when you do so.
A couple of wineries to recommend. The first a little under the radar, the other even more so.
Crociani have a little tasting room and old cellars in the town, but arranging for a visit did seem to bring out very genuine hospitality, even in the middle of them putting together a large export shipment. Those ladies were working hard, yet still managed to make us feel welcome. A cotton shoulder bag was given to us to carry the wine we bought and in it they put a waiter's friend corkscrew. Very generous. The wines I already knew, and absolutely hit the spot I want Vino Nobile to hit (not trying to ape Brunello and not afraid of a little grip).
Daviddi conversely are well out of town, off near Stazione Montepulciano (walkable from there). Arriving a little sodden after getting caught in a rain shower, fresh towels were handed to us to dry off, and after the visit the mother drove us across the way to Poliziano just in case the rain returned. Inbetween the wines (especially the then current Vino Nobile Riserva and the older bottling of it) were one of those cases that makes me think wine critics must taste the same old band of 'name' producers, rather than trying all that is there. They missed (and continue to miss) a good'un, and the wines were much more to our tastes than Poliziano, despite the latter being pricier.
Plenty of others worth a try in the centre, including Dei, Contucci (the most historic, and they value direct contact with customers) and many more. Of those outside, Avignonesi are very good Vino Nobile producers, but their Vin Santo is world class (except that's doing them a dis-service) ~€120-150 a half bottle may sound obscene, but from what I tasted a few years ago, it's very good value!

Not sure if you would even get a taste on a winery visit these days, but I might be prepared to chance it on the offchance.
Here's the listing I made at the time, with one interesting addition I spotted two weeks ago when posting on a travel forum. If you want groceries, then almost everything is in the lower part of town, between the town gate and the bus station (autostazione). The historic part is mostly just good to walk around, admire the views and taste wines, which is fine in my book.
Local taxi: Emanuele Torelli (0)335 6177126
Tourist office – Piazza Don Minzoni mon-sat &
strada del vino – Piazza Grande 7 mon-fri (closed Nov-Mar)
The two ones I've starred were our favourites. La grotta in a handy location for San Biagio ought to have been more touristy, but was really rather relaxed and classy. They ran it very well. Osteria del Conte much more basic/humdrum, but all the better for being a very honest place to eat food that was really very tasty. Worth mentioning Borgo Buio, a rather surreal experience of an owner who is an amateur opera singer and loves to 'serenade' his guests. The food was ok, but no more. Only go here if that sort of surreal experience appeals.
Caffe Poliziano the historic cafe in town, showing a little wear, but strongly recommended for an afternoon selection of their delicate 'mignon' cakes/biscuits etc. to go with the afternoon drink of your choice.
A Gambe di Gatto - Via dell'Opio nel Corso, 34, Phone: 0578.757431 (good food) wed
Ai Quattro Venti - Piazza Grande, Phone: 0578.717231
Borgo Buio - Via Borgo Buio 10, Phone: 0578 717497 mon
*La Grotta - Localita' San Biagio, 15, Phone: 0578 757607 wed
Osteria dell’Acquacheta - Via del Teatro 22, Phone: 0578.75.84.43 wed-mon
* Osteria del Conte - Via San Donato, 19, Phone: 0578.766.062 wed
Ristorante Le Logge del Vignola - via delle Erbe, 6, Phone: 0578.717290
Cafe Poliziano – via di Voltaia nel Corso 27
Trattoria Diva e Maceo - Via di Gracciano nel Corso, 90/92, Phone: 0578.716.951 tue
Caseficio Silvana Cugusi, via della boccia 8 (cheeses incl. Pecorino)
Lo Sfizio (via dell'Opio nel corso 29) for local cured meats and cheese, but also looks interesting for a world-selection of spices
Siena rather surprisingly didn't impress, but most people seem to love it. It felt a little emotionally cold to us (and we're fans of the North, so it's no Neapolitan jibe). It indeed did feel like a city of bankers. The slopes may not be Montepulciano steep, but there is barely a flat part of the whole city, so you'll notice how hard the walking can be. An interesting sight is the outdoor escalators, presumably because they got fed up with walking the same slopes every day.
Oddly the best meal we had was a place (Dolceforte) we stumbled across, and despite being on a less-travelled side street, was closer to a major tourist attraction than I'd normally trust. This place also reinforced the view that Italian artisan beers are just as good with food at the dining table. They may seem pricey vs other beers, but there is often great complexity and fine balance.
The Wednesday market is a huge sprawling affair, with more than it's fair share of tat and repetitive stalls selling pretty much the same stuff. Worth appreciating for the sheer scale of it, and the good stuff mixed in with the mundane. The friday farmer's market however is the most impressive farmer's market I've encountered in Italy (and probably anywhere). Not a huge number of stalls but almost all of 'wow' quality, including the best bread I've eaten in Italy and the best Porchetta that has ever passed my lips. Hopefully the same quality remains.
I had hopes the Consorzio listed below would hit similar heights, but you'd be hard pressed to tell it apart from a humdrum supermarket. Oh well, can't win everything.
The Enoteca Italiana was going through a real fear for its existance when we were there, and as a result felt more like a Mausoleum than a shrine to the pleasure of wine. Worth going on the offchance it's found its feet again.
Wed market – Fortezza Medicea – stadio communale
Tourist office – Piazza del Campo
Buses – Piazza Gramsci
Farmers market in Piazza del Mercato on Fridays
Steam train to San Giovanni d’Asso 9.45am-6.10pm (date?)
Bars on via Banchi di Sopra 22, 25 and via camporeggio 3
Enoteca Italiana – Piazza Matteotti, 30 (noon or 4pm-midnight, Sundays till 8pm)
L'Osteria - Via dei Rossi, 79/81
Osteria La Chiacchera - Costa di Saint'Antonio, 4
* Dolceforte , via Calzoeria 12, open 10am – 11pm 0577 282526 http
://www.dolcefortesiena.it
Gallo Nero - Via del Porrione, 65/67
antica trattoria laquila- Casato di Sotto 58, Phone: 0577.283061
Il Carroccio – via del Casatodi Sotto 32 tue eve & wed (Slow food) 0577 4 11 65
Antico osteria da vivo – via Franciosa 29 (slightly expensive, background jazz & etruscan tombs downstairs)
Osteria Castelvecchio, via Castel Vecchio 65 (includes veggie options & good soups) tue
Osteria boccon del prete – via san pietro 17 (small hectic but with seats downstairs & lighter food)
Al Marsili, via del castoro 3 (elegant) mon
Taverna di Cecco, via cecco Angioleri 19 (inc. Truffles & mushrooms) sun
Ristorant Mugolone, via dei Pellegrini 8 thu sun pm
Osteria le Logge – via dei Porrone 33 mon-sat (big wine collection, but skip the pasta)
Enoteca San Domenico, via Piangiani 9 sat pm sun
Tullio ai tre cristi, vicolo di Provenzano 1/7 (old place) wed
Grotta di santa caterina da bagoga - Via della Galluzza, 26
Tel. 0577 282208 (Slow Food) sun eve & mon
Antica Pizzicheria Chugiana(?) / di Miccoli – via di Citta 93-95 (meat cheese etc.)
Antica drogheria Mangandi, via di Citta 71/73 (not cheap but fine selection sun
Fattoria Belsedere, via Camollia 29 (pecorino, salumi etc.) sun eve
La Compagnia dei Vinattieri – via delle Terme 79 / ang. Via dei Pittori 1 (Enoteca with food)
Consorzio Agrario di Siena – via Pianigiani 9 (local food co-op) sat pm sun
Nannini – via Banchi di Sopra 24 (cafe/aperitivo / desserts)
Forno dei Galli, via dei Termini (via di Pontani underpass – bakery +)
Pasticceria Bini – via Stalloreggi 91/93 (cakes /biscuits + vin santo etc.)
Pasticceria Le Campane – via caduto di Vicolbello 37/39
Torrefazione Caffeteria Fiorella – via di Citta 13
These notes from 2010, so there will be a little change, though change is often slow in Italy
Regards
Ian