Well our two kids have used Bobo's at Flumserberg and the Snowli school at Grindelwald. They've also had a few hours each with a private instructor at Flumserberg. IMHO, the Bobo school was OK but I agree with the comments about group size, especially at weekends it's very busy. The private tuition, also at F'berg, was very good but not cheap at CHF 170 for two hours. The Snowli school at Grindelwald was the best though with excellent facilities and a staggering number of blokes and blokettes wearing Swiss Ski Instructor red outfits. The children did a one week full day course at Grindelwald and I think this was the best tuition they've had. Both of them really enjoyed it and the teacher/pupil ratio was good. The facilities are excellent.
The cost for two children for one week was around chf 800.