I second these questions. Answers will help posters provide useful suggestions.
Virtually all top colleges and quite a few others besides will offer very rigorous educations. High schoolers are often used to a lot of busy work in AP and IB classes; there is much less of that in college.
I’ve often wondered how much of Chicago’s reputation comes from taking pride in how much work one has to do and whether the “Duck syndrome” common at schools like Stanford leads people to wrong conclusions about relative workloads. I once compared notes with classics majors at other top universities (Brown, Hopkins, Chicago, Penn, etc.) and found that we all had to translate about the same number of lines each night and had roughly comparable workloads. Additionally, the department I’ve spent time in at Chicago is very similar to that of other top universities. I can’t speak for all majors at Chicago, of course.
The quarter system tends to be more fast-paced and stressful than the semester system, though.