Should the CERN hostels be full, or should you prefer to stay in Geneva, we advise you to consult your favourite on-line booking portal (www.booking.com, www.tripadvisor.com, www.trivago.com, www.expedia.com etc.) and to contact the hotel directly in order to identify the lowest tariff available for CERN users and collaborators (preferential tariffs may apply in some cases).
Hotels in the vicinity of "Gare Cornavin" (Geneva's main railway station), or along "Route de Meyrin", are particularly recommended. Tram number 18 links Gare Cornavin to CERN in 20' (see timetable on the TPG's webpage
at this link).
Notice that, by staying in hotel, youth hostel or at a campsite, you are entitled to receive a personal and non transferable Geneva Transport Card for free, which will allow you to use the whole public transportation system of Geneva for the length of your stay for free. This includes buses, trams, trains, and yellow taxi-boats - Mouettes. Just ask for it upon arrival on the reception.