There are several hotels at the start/finish area in Gluringen. They are booked out fast so you'll try to get your hotel room booked sooner than later. You will also find many hotels in the close by villages just go and Google it. If you're booking a room ask if they offer a Swiss Alps 100 discount. Several do and it doesn't hurt to ask but it will only work if you book on the hotel's website or by mail/phone call. It will not work through a 3rd party booking website.
There are two camping facilities very close by the start/finish location. Camping Augenstern (1.5KM to start) and Camping Brigga (2KM to start). No camping is allowed at the start/finish area.