Have you considered building in a feature where teachers from the same school can, via their planbook, automatically signup/sign-out for school wide resources/rooms/equipment?
For example: As a science teacher I sometimes need to use the Gym or media center, so in my planbook I put a note to myself under my "Prep" category with a "G" or "M" so I know to reserve the room...but then I need to actually still check and reserve it on my end. Or as another example: Our School has mobile computer carts, so in my planbook under mu "Prep" category I put a note to myself with a "C1" or "C2" to reserve a computer cart...but then I still must go an find an available cart and sign up for it. The examples go on and on: shared lab space, shared DVDs, shared science or gym equipment, use of Kitchen or commons area, etc.
Then there is the added problem of when I need to bump a day I need to adjust my reservation....so I thought that it would be helpful if a teacher could first of all have an area/feature where they can make room/equipment reservations or requests, and that such a reservation would be synced to a lesson. So when I bump a lesson the reservation either bumps with it automatically or a notice pops up that the resource has already been reserved so a new resource will be needed.