Recommended driving stop between Colmar and Chamonix?

Hi All,
My family will be traveling to France in the second half of August for two weeks. After seeing Paris, we plan to train to Alsace, rent a car and stay there for a few nights to see the area and the towns. Then we will drive from there to Chamonix. Do you all have a recommended stop for two or three nights in between these locations?
I've heard Montreux or gruyure are worthy destinations? Other ideas?
Thanks!