I just did the Best of Italy tour last October with a single supplement.
Here were the hotels and some comments:
Varenna: Royal Victoria - I made a tactical error here. I'd gone up 2 days early from Milan and splurged on the Balcony rooms facing the lake. It was quite a come-down to move to the tour room on the front of the hotel. I had a view of the square and the church so it wasn't viewless but nothing would have been like the balcony room, lol.
Castelrotto: Hotel Cavallino d'Oro -Oh my....the door to the room looked like a cute Hobbit hole but inside it had vaulted ceilings and was so cool! Huge bathroom as well. Some tours stay up at Compatsch at Hotel Seelaus.
Venice: Hotel Serenissima - This was the smallest room although the bathroom was fairly good-sized. It was the only room on this trip that had a single-size bed - or maybe a small double bed.
Florence: Hotel Accademia Firenze - I'd stayed here long ago on my first RS tour. My room was big and I had a huge bathroom
Cinque Terre: Albergo Pasquale - I actually stayed in the very same room as on my previous Italy tour, lol. Large room, faced the beach and sea.
Siena: Hotel Chiusarelli - I had a cute balcony in this room as did many other tour members. Room was big, bathroom was odd as is sometimes the case in a retro-fitted buildings - long and narrow.
Orvieto area agritourismo: Altarocco Wine Resort - I had a giant room here. King bed, I think, huge bathroom.
Rome: Hotel Aberdeen - Room was fair sized but bathroom was pretty tiny and shower was one of the very small corner showers that I've had before in Rome.
I'd have no problem recommending this tour for a solo traveler on a single supplement! It's a wonderful, wonderful tour! Do go to Milan a day or two before the tour starts both for jet lag, possible travel delays and to see the Last Supper and the Duomo. I also recommend staying in Rome another day or so if you can do it.
If you are interested, here is my Trip Report.
https://community.ricksteves.com/travel-forum/trip-reports/best-of-italy-sept-30-october-16-2022