The planners I’ve found in the stores have weekly and monthly calendars. I’m looking for one with a daily planner, as well. Any suggestions?
Jumped the gun and posted. I found one at Staples. 
This is what my kids used before their school started providing planners. It is weekly but there is room to daily plans.
Otherwise you can look at the other daily planners that FranklinCovey makes. I have been using this system throughout my professional career and find it invaluable.
For future reference and for anyone else who needs one, Barnes and Noble has a really nice selection of academic year planners with daily calendars. I used one for years just to track my kids’ schedules.
I found an amazing planner, and it really helped my younger D last year (just ordered another one for her this year):
https://www.amazon.com/gp/product/1462519563/ref=oh_aui_search_detailpage?ie=UTF8&psc=1
I get ones like this for my son: https://www.amazon.com/Student-Planner-2016-2017-School-Content/dp/B017IXJT1M/ref=sr_1_1 It has a column for each day with 7 subjects/day.
Both of my kids love the one page/day Dayminder calendar so they have plenty of room to write in homework and other things.
Check out the day per page printable insets here: http://philofaxy.blogspot.com/p/diary-inserts.html