My Classes page is too busy when I have Summer and Fall classes open for registration?

I think the best way to manage the way the classes appear on your website is by using curriculum groups (Under Setup/Curricula). 

You could create a group for regular (spring/fall) classes and a group for summer classes. By naming them and describing them you should be able to make navigation of your particular choice of curricula simple for the parents.

You can also segregate Kindermusik classes from Piano classes using this method.