We are visiting Italy in late September - 4 60-somethings. Second time for one couple (concentrated on Rome and Umbria first time), fourth time for other couple (visited all major cities previously). Trying to decide best itinerary for a 7 day trip. Prefer to concentrate north of Rome, either Tuscany area or Milan/Venice/lake regions. Also hoping to base out of a city (not a major one) for at least 3 days or so to enjoy the ambiance of Italian life. Any suggestions?
You could spend a week in Tuscany using two cities as bases: Siena and Arezzo might be interesting.
If you want to go to the Veneto, have you been to Padova, Verona, Vicenza?
Or Emilia-Romagna (Bologna, Ravenna, Ferrara, Modena, Parma, Cremona? This would be my first choice.
Go to Venice if you haven't been there, 2 night minimum.
Then head for the Dolomites, stay in Ampezzo
Bolzano is a great mountain town. There a a few small towns you can take day trips to. Also, it is located in the German-speaking region of Italy so you'll be able to experience something a little different than you would in other Italian towns.
Without knowing any of your interests, I would say stay in Tuscany and explore the various hill towns.
Things are closer for day tripping.
Of course, if you have never been to Venice and really want to see it, you can easily plan a week with Venice and another region only a couple of hours away ; you have some suggestions above on those.
I will say end of Sept. the Dolomites would be the end of the season. Lifts may not all be running and expect some snow at highest elevations by then. Does make them prettier but a different kind of vacation then you may be looking for having to pack your winter clothes and all.
Again, not knowing your interests, but I've traveled around Italy quite a bit and I'll say I personally didn't enjoy Milan or Turin as much as other parts of Italy such as the region around Venice (including all the way from Verona to Ravenna) or Tuscany. The mountain & lake region north of Milan, though, is spectacular.