If you are missing the mountains, there also lots to do in Summer. Valais has over 300 days of sunshine a year, there are many top golf courses, summer skiing, hiking, biking and much more here are a few useful websites:
Mountain Biking http://www.valais-decouverte.ch/
Grand Raid http://www.grand-raid-cristalp.ch/en/home (mad bike race my husband does this every year!!!)
http://www.valais.ch/fr/index.cfm
There are just a few things there is so much more.