If you haven't enjoyed it already, you can give
Azumanga Diaoh a go. The focus is mainly on the lives of the average highschoolers who just know how to have fun. Each episode another chapter of school life, twenty-six episodes spanning these girls' freshman, junior, and senior years. Very funny I must say.
Gakuen Alice and
Zero no Tsukaima also have the school setting, but there is a magical twist to these two stories.
The other current series,
Ouran Host Club is also school based, but the story here revolves more around the club and their activities.