I'll agree with Liz's assessment of the Hotel Selene. I stayed there for a couple of nights before my first RS tour in 2013. The tour hotel was Hotel Sonya which is right down the street. I would easily stay at Selene again and I agree with the comment about the stairs. One RS guide told me that in the older buildings in Rome the ceilings are really high so you actually have 2 runs of stairs for each floor. The AC was good and the bathrooms were way bigger than the ones at the Sonya.
I, too, found the desk staff there very nice.
I would stay as many days before and after that you can. Before, not just to get over jet lag so you can hit the ground running with the tour but to give yourself some lee-way in case of flight cancellations or diversions, etc.
I've done 8 RS tours, 5 of those as a solo participant. I have always had a wonderful time! You will want to check out what you want to do in your free time so you have a plan but then have ability to change it up and go with something else that sounds interesting that others might be doing. OR you might have chosen the most interesting option and others might want to join you!
On your Switzerland day, don't fret. The guide usually organizes something that people can participate in if they choose. If the weather is clear s/he might organize a trip up the Shilthorn (they may pay for the tickets so they can get you a group rate, then group members will reimburse) or possibly a trip down to Truemmelbach Falls.
That reminds me of something else - on the 21BOE the guide did several optional dinners and other things. One was the Schilthorn, another was a gondola ride in Venice. I'd suggest you do everything the guide offers, lol!! The cable cars in Switzerland are expensive but just do it. The pay-off is great!
