Siena, Orvieto or Assisi

Which weekend? Easter is April 20 and April 25 is also an Italian holiday

Orvieto for the weekend-no car needed-super easy on train and it’s mostly day visitors so the evenings will belovely

I suspect Assisi will be jammed with pilgrims
Siena is a bit of a pain to get to although bus works

I wouldn’t expect anywhere to be not crowded

Of those three, Orvieto is my favorite. I loved the Cathedral, the Etruscan museum and the market. I didn't get a chance to visit St. Patrick's Well. Siena is fabulous as well.

Assisi, I didn't enjoy. Mostly because I am not a fan of Catholicism and to me, there seemed to be a lot of performative displays. If you are Catholic, I believe your experience will be different than mine.

All three places are wonderful in their own unique way. From Florence, I'd take the bus to Siena. It drops you off at the entrance to the historical area you'll want to wander through. The Duomo and its museum are very special and I highly recommend doing both. Orvieto has some spectacular views of the countryside. Lots of good food! Assisi is my favorite. The churches are filled with St. Francis,history (800 year anniversary) but also there are Roman ruins under several of them. And under the Roman ruins you'll find some Etruscan ruins. It seems that for well over 2000 years, Assisi has been considered a place of peace. YES tour groups are a nightmare during the day but they do tend to disappear late in the afternoon. The Assisi that celebrates all the best starts around 5 o'clock. The streets are calm. Stores are open but not crowded. The bars are ready for relaxing and 'just living.' Check schedules, churches and museums may be open late because of the Jubilee. The Basilica San Francesco is certainly worth a few hours. I prefer to spend my evening hours on the Piazza Comune which is where Santa Maria Sopra Minerva church is and near Basilica Santa Chiara. Basically, head uphill from San Francesco - you'll find it. I'm planning almost the same trip now. I'm looking at 3 nights in Siena and 4 nights in Assisi. Orvieto didn't make the list,

Of the three, Siena is my favorite. But Orvieto would be the most convenient from Rome and is also delightful. Since you just have a weekend, I would not try to do both towns, but would opt for a train to Orvieto.
Happy travels!

Train to Orvieto is approx. 1 1/2 hrs. Train to Siena is approx. 4 hrs. I love both places, have stayed in both. If you had a car you could stay in Orvieto and/or Assisi and visit both. I would consider how much time do you really have to spend in each town, and how much time do you want to spend traveling. Assisi is the most touristy FYI.

Thanks everyone for the feedback. It's the weekend of April 4th.