I will be visiting Chamonix in March. I am considering purchasing a 3 day rail pass for travel to Lyon, Grenoble, and Annecy on separate day trips. I understand that I will have to connect in St. Gervais Les Bains to get to those cities. But I am not sure of how to get to St. Gervais from Chamonix. Likewise travel back to Chamonix as the return trip for each day. I have ridden trains throughout France but I have not been to Chamonix. Is train travel to / from Chamonix straightforward?