Welcome to Flyertalk and a great first question ^
Neither program is very rewarding when it comes to free nights
In fact as I know it Swissotel doesn't offer any free nights that you can earn by staying and is a non point based program.
However Swissotel Club Gold has some very nice benefits like free breakfast buffet,late check outs and a suite upgrade for 25 dollars more or free depending on the individual hotel policy.

Swissotel does runs free night promos with partners like Amex from time to time. Typically they are buy one or two nights get the next night free
The rates are usually higher and you must take the free night during your revenue stay
They also offer 500 Delta miles per night on stays up to 5 nights and the standard 500 miles for most other airline partners.

The Sofitel program has free nights when earning points in their program but be prepared to pay high rates to get them and if I remember correctly points expire.
I doubt you will get many replies on these programs because both companies are clueless how to market and communicate to frequent travelers in an internet based world. And that’s a shame as they have some great hotels as you probably already are aware of.
Perhaps some in the int community here can shed some more light on these two programs.If free nights were my goal with the two mentioned programs obviously one would have to go with Sofitel.But you pay a premium
IMO the major programs are doing a much better job at rewarding frequent stay guests
Cheers