In June this year I spent six nights in a silent retreat at Monasterio Santo Domingo de Silos which is not directly on the
Camino Frances but is close to Burgos which is on the Frances.
Retreats at this famous monastery (all services are held in Gregorian chant) are only offered to males and they require you to pre-book. I think that the minimum stay is three nights but please double check this with them directly. There is probably also a maximum stay but I don't know what that is.
Leaving aside the services, which are all in chant, the monks only speak when required (for example to register you and point out safety procedures or to remind you not to speak) and never during meals. Depending on how many other people are on retreat with you, you will either eat separately (more than four others) or with the monks (three or less). If you eat separately from the monks then you are permitted to talk during your meal.
You are expected but not compelled to partake fully in the religious life of the monastery. If you read Spanish then this is the timetable that you will follow.
Only the monks work during the green periods, you are free to choose your own activity and you are permitted to leave the monastery to visit the town or the surrounding area (nice walking), however it is frowned upon to use the monastery as a base while spending most of your time exploring the surroundings.
You are on retreat and so expected to follow your own religious, spiritual or contemplative path while at the monastery. You are encouraged to be purposeful. If you attend the services and meals then you are expected to be strictly on time.
If you stay then you have access to almost all of the monastery including areas that are out of bounds for tourists and day trippers except for the library and the monks private rooms. It is possible to get access to the library if you can show a genuine need as a bona fide researcher.
Here are some photos showing my room, some behind the scenes areas and areas that are open to tourists.
Room and private entrance.
Areas not generally available to tourists.
Areas available to the general public.