I want high school to include things not just related to high school.
A romance system to include crushes & first dates, proms and asking Sims to prom, high school graduation, applying to university earlier/planning their future, boarding schools for child aged that'll help them get into high school, field trips, bring back private schools with the headmaster.
More after school programs that are teen specific besides drama club and boy scouts. Like internships, tutoring younger kids, etc, touring universities, going to work one day with their parents.
I like for parents to be involved, like PTA meetings, the household attending the graduation, parent/teacher conferences, giving permission to date, teaching them to drive, etc.
I'd love to see acne and body odor. I think this is the age group for it. Options for teens to be rebellious and randomly change up their hair and makeup.