i've lived in and around geneva for 27 years (1983-2009) and have now been living in Vancouver for almost two years.

Geneva was great in the 80s. Virtually no crime, no unemployment, little traffic, etc. In the last 10 years it has gone downhill drastically. Downtown Geneva is a dump. Areas that I used to gladly walk around in are no longer totally safe as they once were (e.g. Paquis in front of the station). So we moved to Nyon, 13 minutes away by train. Well, usually. Whereas in the 80s you could set your watch by the train and you could almost eat off the floor of them since they were so clean, today the train from Nyon to Geneva is late half the time, it is so crowded that even with a first class pass you often find no place to sit and people selfishly occupy two or three seats. The freeway is at a standstill as is most of the city at rush hour. It is so saturated that if there is the slightest mis-hap, the who place just locks up for hours. The police do nothing. I was on the city bus last time i was there and a druggy was "chasing the dragon" right on the bus. This refers to putting heroin on a piece of foil and holding a lighter under it and inhaling the fumes. I actually called the police while this guy was doing that and there response was "what would you like us to do about it?" Check out the open drug scene in front of the cinema just to the left of the train station. go for a walk in park des eaux vives and check out all the deals going on in the bushes but be careful not to step on the used needles. A coworker of one of my good friends who works at caterpillar was stabbed and killed in downtown geneva for his blackberry.
Rent is OUTRAGEOUS and that's IF you can find a place to rent. Another good friend built a duplex (side-by-side) house for a mere 3.5M and rents out the other apartment for well over 10k per month and that's not even in some exclusive neighborhood. You'll be hard pressed to find something suitable for a family for less than 3.5 to 4k/month and it won't be anything special. it's ludicrous.
shops close at 6:30 in geneva during the week, 6 or so on saturday and are closed on sunday. expect very longs lines at all times. Out in Nyon it's even worse since there are only two supermarkets to feed a region of close to 50k and they close even earlier.
i could go on and on but i'll quit here. needless to say, i think geneva sucks. but a lot of brits compare it to the UK and think it's great. "hey, it only takes me an hour to drive to geneva. in london it took me two hours!!!"
check out glocals.com for some info. make sure your contract includes a relocation service. PM me any time if you have specific questions. insurances, doctors, dentists, areas to live, etc.
Be sure to check out schools for your kids if you plan on sending them to english speaking ones (Ecole International in Geneva or Founex) as they have long waiting lists and are quite dear.