The most appropriate option is still Abruzzo. The cost of living here is 30-70% lower than in Tuscany or Umbria. A couple of retirees here can live on $ 1400 including rental properties. In the mountains, ski resorts and bases work in the winter, and in the summer holidays on the Adriatic coast are popular.
Ciao! I went to Siena in the 17th year and was pleasantly surprised. I found entertainment on these resources https://www.tripadvisor.com/Attractions-g2043779-Activities-c61-t62-Province_of_Siena_Tuscany.html. In Siena I learned how to write narrative essay for my university