Number of nights in Florence and Orvieto

I'd split them up further, if not reverse the number of nights, seeing as you do not have a car. Florence should be given two full days at least, some will say weeks, and include a trip on the number 7 bus up to Fiesole. You can day trip out of Florence to a number of places by public transport (Siena, Lucca, wine villages), not sure about Orvieto (which itself is a very attractive place).

I haven't investigated the transportation from Orvieto to other towns in Tuscany or Umbria. Before you stay in Orvieto for four nights without a car, make sure there are good transit options for the places you are thinking of visiting from there.

Florence has buses to much of Tuscany, but even then, some towns will require changes. On Sunday, buses can be sharply curtailed or non-existent. And Orvieto isn't a regional capital like Florence is.

I like Orvieto a great deal, but it is not a terribly convenient base for side-trips via public transportation. I suggest researching how you would get from Orvieto to places you tentatively think you'll visit from that base. That may cause you to adjust the number of nights you spend in Orvieto. I do think the town has more than a full day's worth of things to see and do, unlike some of the smaller hill towns that are better for stops of just a very few hours.

You don’t say what season or month you will be in Italy, although that probably does not change the response to your question. As much as I love small, ancient hill towns and Orvieto, I agree with others that you should switch your plans and spend four nights in Florence and two in Orvieto. There is so much to explore in Florence, and so many day trips are easy from Florence, either on your own or by day tour. The one exception might be if you want to stay at an agritourismo just outside Orvieto, and take a day toward the end of your trip and just kick back and relax.

Thanks for the replies so far! We will be there in early June and did find some tours that leave from Orvieto.

I agree with changing it to 4 nights Florence, with very easy day trips, and 2 nights Orvieto. Much as I love Orvieto, we had a car which made it easier to get to other small towns.

Florence 4, Orvieto 2. Another reason why Orvieto isn't the best place for day trips is that the historic center, where you'll want to stay, is on top of the hill. To get to the train station, you have to take a bus or a longish walk to the funuvia, which stops running around 8 pm, so you'd want to be back before then. The Florence train station and intercity buses are in the historic center.

4 days in Florence and 2 in Orvieto for all the reasons previously mentioned.