Italy - Good towns/cities to take a relaxing vacation from your vacation

San Casciano Dei Bagni

One way of determining “size” is population, which might not exactly convey the feel of a place. If precisely matching Sorrento’s population isn’t the only way to measure your goal, then comparable places, where we stayed on a 2012 trip that included both Sicily and Sorrento:

Castelveltrano, in the heart of the island. It’s known for a long, steep tiled staircase to reach the upper part of town, and its ceramics. Population is apparently a surprising three times the population of Sorrento, but it would work. We had a rental car, so getting there without one might require a little extra effort, but that would be worth it. Otherwise:

Southeast Sicily has Modica, perhaps the epicenter of chocolate (don’t tell Belgium, Switzerland, Mexico, etc.), amazing upper and lower towns, and yet it’s a genuine place. Population turns out to apparently be twice that of Sorrento, but it would also fit your wish.

Smaller than either, but surprisingly still a bit more populous than Sorrento is Erice, on the western tip of Sicily, high, high above Trapani.

I think your idea is perfect: SORRENTO! For more than a decade, Sorrento has been my "I deserve this" place. Day time, evening, late night strolls. Plenty of food options - all very satisfying. The most beautiful sunsets. I always stay at il Nido (ilnido.it), which is above the city and easily accessed by their hourly shuttle. It also has, IMHO, the best restaurant in Sorrento for breakfast (free) and sunset dinner on the deck where you can watch the diamond necklace surround the Bay of Naples. Check out Vesuvius - is that a cloud? or smoke?

Another vote for Sorrento

Unless you’ve been and are looking for somewhere different?

Second choice Salerno
Direct train to Rome

Cefalu is an hour train ride from Palermo and where the elderly men still dress for their evening passeggiata and the cannolis don’t get any better than what you’ll eat here. This is a fishing village so you’ll eat well and for some reason is not a stop on the Sicily tour. I prefer it over Sorrento and dining along the coastline makes a perfect setting.

Why not the seaside towns north of Rome where you'll meet only EU tourists? As an example, what about a little village like Capalbio?

Or the Pontine Islands in front of Rome?

There are other options to the touristy Sorrento and the Amalfi Coast, meeting only people from UK and USA is not yet mandatory.

I'm going to suggest staying in Sicily. If you are going on a Rick Steves tour of Sicily, then how about a slight change in scenery......Taormina. One hour north of Catania, plenty of seaside hotels and cafe's, smaller than Sorrento.

Or head on over to Puglia--Lecce, Galipoli, Otranto, etc. Like Dario said, the tourists will mainly be Italians and not Americans/British.

Stay in Sicily, unless your flight home is from the mainland. For example if you leave from Naples then Sorrento is perfect. If you fly home from Palermo then not so much.

So much smaller than Sorrento is Scopello. The village is tiny but the walking/beach aspect is fabulous. Look at the Zingaro reserve to see the nature. There are bigger towns around, I vaguely recall them being nice but I mostly focused on hiking/beach/and Scopello.

I’m sure you will be in Siracusa anyway, but one could easily use the island of Ortygia for the purpose you describe. It’s a great place to just be and explore.

Since your trip is to Sicily my recommendations are all located there. Consider beautiful seaside Mazara del Vallo. It is not on the typical tourist radar. It is connected by train and bus (I got there by train from Palermo and left by bus). It is famous for its combination of Christian, Jewish and Arabic history, which is also ever present in its cuisine, architecture and street murals. Lots of narrow alleyways to explore and a short trip from the spectacular ruins of Selinunte. We got there by taking a combination of train from Mazara del Vallo to Castelvetrano and a local bus to the ruins that stopped right at the train station.

Nearer to Palermo you might take a look at seaside little Castellammare del Golfo or bigger Trapani.

Someone suggested Cefalu, which is lovely and a great destination but be aware it will probably be filled with tourists and daytrippers. Same is true of Taormina, spectacularly beautiful and great scenic views but both are prime tourist destinations and can get very crowded. During your two week trip around Sicily do try to visit both of them but they will have lots of tourists.