There's a company called Les Elfes http://www.leselfes.com/ who organise skiing trips in the winter and various types of activity holidays in the summer. They are based in Verbier but have chalets over the other side of the mountains in La Toumaz and in Crans Montana. They seem a very organised set up and have been doing these for many years. I don't have children so can't comment on personal satisfaction but I am thinking of using them for business purposes.