Suggestions 2-3 nights late Sept, nice town, solo female

Turin would be perfect, though it is a city.
If you don't want to backtrack, maybe Vicenza? I saw an episode of House Hunters International set there and it looked lovely.
I've always been enamored with the thought of Chioggia myself.

I don't believe you can find a wooden village with widows in black carrying baskets to shop for dinner. That said, you might look into Reggio Emilia, which is a smaller but prominent city without famous monuments. I used to go there for business, and it is rare to hear English on the street. It is sophisticated enough that you should be able to strike up conversations with the locals, and it's easy to take a train somewhere (Bologna, Florence ... ) if you get bored. It is not a common answer to your question, so you should look it up before deciding.

I spent a day once in Stra, very close to Venice. I think it's mainly shoe manufacturing, but at least it's small. It has one big sight, a famous villa with baroque interiors.

it might be larger than what you're looking for, but Padua might fit the bill. As might Verona or Vicenza, which are smaller. All are reachable by rail.

I agree about Padova, this is a day we spent there: https://slowtravelitalyspain.blogspot.com/2019/09/day-trip-to-padova.html
But actually I'd advise you to reconsider about the Lakes. Lage Garda is very conveniently located on the trainline between Milan and Venice so you could choose between Desenzano, Sirmione (the quaintest but also the most touristy) and Peschiera del garda. Personally I'd choose Desenzano - Sirmione attracts hordes of foreigners whereas Desenzano is popular with people from Brescia out for the day too, friends, families, definitely not just romantic couples, lots of bars, restaurants and life. And easy to visit the rest of the lake by ferry. Lake Garda is the sunniest and warmest lake with the mountains in the background, a nice change from the mostly city and sights tour you'll be doing afterwards

Perhaps Bergamo might fit the bill? Full disclosure I have not been there, but it did pop up in research that I did for my own upcoming trip. It’s a city but not a big one, and is very convenient by public transport to Milan. Looks like a really nice city to visit.

I vote Lago di Garda too! I stayed in Peschiera del Garda and it was a delightful little town! I bet Desanzano might be bigger and have more to do, but I liked taking the ferries all around and loved shopping at the weekly market at the town of Garda. I definitely heard a lot of German spoken though! VERY easy to get to Venice.

Padova, Verona or Bergamo-we’ve been to all and liked them all
Probably liked Verona the most-it’s very pretty has a very classy feel, a few sights. Plenty of cafes and piazzas
I think Sept is past Opera Season
There are lots of day trip possibilities as well

Another possibility is Mantova-have not been-it’s on our list for next trip
Looks very nice and not too touristy

Hi, I have traveled solo to several cities in Italy in northern Italy that you might enjoy. I am in my 60’s and have traveled solo there multiple times after trips with my husband. You will have a wonderful time! Here’s the easiest ones that sound like something you might like:

Stresa on Lake Maggiore, my favorite spot at the lakes to get over jet lag! An atmosphere of elegant old hotels with the charming little islands a few minutes by ferry. i move the last day over to stay on tiny Isola Bella - the one with the gorgeous, formal Italian Borremeo garden & villa. If you’re going here, skip taking the train into Milan and just take the Alibus from Malpensa directly up to Stresa. Stresa will feel less “medieval piazza” than the others.

Bergamo - very easy to reach by train from Milan. Stay up in the Citta Alta section - very atmospheric and has interesting history (read about on-line) and some stunning colored marble architecture. I will also add my trip report - highly recommend the sketching & watercolor instructor!

Cremona - if you’re interested in the Stradivari violin history and love an authentic town, you will love this town! It was my first city to return to after the pandemic years, and I started getting teary-eyed walking into the piazza! The cathedral interior is stunningly filled with frescoes. The piazza in the old center in the evening is exactly what you are describing.

Verona - a very easy city for tourists. A nice location to see some historic sites - Roman Arena, etc. and has a Verona Card to see multiple churches, etc. I have also taken a city bike tour here which was a fun way to learn more about the history as we rode for a few hours of mostly level riding. An advantage is that it’s directly on the train route to Venice. It’s actually where my husband & I went for three days before starting the RS Best of Italy tour.

Padova - another city on the direct train route. It’s another nice town, but I prefer all of the ones mentioned above more. Look up the top sites on TripAdvisor. You can easily enjoy your time allotted in Padova.

If you choose Padova or Verona, look at flying into Venice, instead. Ferrara is another option that is handy to stay if you fly into Venice. And if you go there, take a day trip over to Ravenna for the amazing mosaics!

Hope that helps!

Here’s a couple of solo trip reports from 2022 & 2018 with names of hotels, etc.

https://community.ricksteves.com/travel-forum/trip-reports/trip-report-please-do-not-comment-until-i-change-the-title-filling-in-the-report-thanks

https://community.ricksteves.com/travel-forum/trip-reports/solo-trip-to-italy-2018

First choice would be Verona, and second would be Vicenza. Both easy to get to by train from Milan. In late Sept. neither one should be too crowded, so you can just kick back and relax withour the summer time crowds.