We would totally recommend staying at Castello del Duca. It’s such a beautiful location and getting in and out of Rome by train is easy and cheap (1 euro each way), with regular, clean trains. Sette Bagni has 2 supermarkets within walking distance of the accommodation so self catering is easy too.
Fabio was a great host and even came and picked us up from the station.
Italy at the moment seems to be handling Covid really well - everyone seems to be adhering to wearing masks, shops and attractions all have sanitisers and the local supermarket even has a self temperature reader!