Versoix (workshop location)
The normal venue that we would recommend is the Lake Geneva Hotel, which is very close to the Versoix train station (Versoix gare). Unfortunately it is quite expensive this time, as there is an overlapping event in the area. If you manage to find a room at a reasonable price, it is still our top recommendation.
There are also a couple of other hotels in Versoix. They also seem to be expensive for the dates in question, but if you find a good deal, they would be the most convenient.
Nyon (25 min train ride, including one change)
Versoix is the end of the Canton of Geneva, which is where the event is taking place. Across the border the hotel prices drop quite quickly. Nyon is the first good-sized town along the train line, and there are a few hotels near the train station. These hotels have much more reasonable prices. We therefore recommend Nyon to anyone who is not coming with their own car. Assuming a few people are staying in Nyon, we will organise a van between the venue and Nyon.
Geneva (15 min train ride + getting to the station)
Geneva is a 15 minute train from Versoix, with regular train (and bus) connections. There are still some hotels in the area at reasonable prices, but they are in general more expensive than usual, especially those close to the train station, again due to the overlapping event. So if you want to stay in Geneva, please do book early!
CERN (15 min train ride + 25 min tram)
For those of you who have access to CERN, it looks like there is a decent amount of availability. It may be your best option. If there are a few people at CERN (max 4), Steven can probably pick you up on the way to Versoix.