Time of year can be a factor, as the countryside has stronger appeal in the warmer months, cities in the cooler.
Length of stay influences our decision on bases. The longer the stay, the more desire to change the 'base', so the everyday has a different feel to it. How long does vary between people, but between 4 and 7 days isn't a bad benchmark, though in more energetic days we'd have the odd 3 day stay.
Events can be ideal for a solo traveller, be they festivals, exhibitions, organised walks, tastings etc. It's a bit of an effort to find these, but IME that time is well spent for the experiences, and where you'll get to meet Italians as much as other tourists. Indeed we've in the past let them drive the scheduling / location of our holidays. The tourist offices usually have a solid listing of them, but there are other aggregator sites, or just individual listings. I tend to look at the same time 1 year prior to our likely stay, to pick up on annual events. Try to seek out locally run organised day trips for a better mix of locals / Italian tourists / international tourists. As a solo traveller, they'll help give you that regular interaction, and also offer the option of meeting up with people you got on with, for a meal or a drink later in the week.
We did a 3 location trip to Tuscany, taking in Montepulciano, Siena and Pisa as bases.
Perhaps surprisingly Siena was the least of them in our eyes, as we found it an odd combination of a rather reserved banking city, combined with a strong thread of mass tourism. Occasional super highlights e.g. the Saturday morning farmer's market where everything we tried was genuinely excellent.
Pisa too suffers from mass tourism, with two decidedly crass threads of it from either train station to the field of miracles, and around that site. When people describe Pisa as dirty/disgusting, it's because they've just experienced a half day trip with such a singular focus, and unwittingly have fuelled that problem. However head east to the city itself, and there's genuine charm, good (and surprisingly good value) food, a solid daily market, and a vibrant main shopping street for an evening passeggiata.
Montepulciano well worth considering with wine being an interest for you. Drop in tasting rooms abound (a rarity in Italy), though even booking in advance can make for a more convivial visit (e.g. when we visited Crociani's tasting room, with the industrious ladies packing loads of orders making us feel very welcome and appreciated. The wines super as well).
Lucca is lovely as well, and one of those rarities in Tuscany, of having a train station that's actually close to the centre (coaches, known locally as 'Pullman'
) are often the best way to travel, dropping you off in the centre. Enoteca Vanni a super wine shop and I believe they run organised tastings, so that might be one influence in trying to tie your visit into one of them.
Livorno worth considering as a day trip, with a fish soup / stew their food speciality.
Colle val d'Elsa (known rather oddly as simply 'Colle' locally) was a surprisingly good day trip for us, and enjoyable enough to consider it as a future base. Glassmaking is their big industry, but it seemed to be squarely Tuscan, but without the blemish of mass tourism.
