In official Tour, nights are supposed to take place in Geltenhütte, in Iffigenalp, in cabane des Audannes and hotel Sanetsch.
You can sleep in Wildhornhütte, just for pleasure or if you want a shorter day or if you are on variants. You can also lunch there on your way to another hut. In any case, it's really a good idea to stay in.
The Prarochet hut and the Wildstrubelhütte are just aside the Tour, and must be kept in mind as good altitude references. They can also be used to sleep in for people doing a long trekking from Alps vaudoises to Alps bernoises.
The "Auberge du Sanetsch" is a restaurant not a cabane. You can eat but not sleep there. If you have the car you can drive to "hotel du Sanetsch" where rooms have all the charm of a mountain hotel (look at Sanetsch sheet).
Fore more details, click on the lodging possibilities.
All huts must be reserved before you start trekking. Even in low season, the hut can be full because of a group, and you must see again your organisation. Hut guardians look in advance the meal preparation and organisation of dormitories. So not to make a mess of the hut, the reservation is compulsory same as annulation if needed.