I use the calendar in Outlook email public folders so teachers can view 24/7.   The labs are self-service; staff have rights to sign themselves up.  The mobile carts are on a request basis; teachers can see the calendar and then they request it.

You might want to limit how far in advance teachers can reserve--otherwise you might have someone book a lab every Monday and Wednesday for the whole year.  Been there.  Awkward.

If we were a Google App school, I'd switch to a Google calendar.  Students often can't remember which lab they are scheduled too, either, and they could see it themselves.

Good luck!

Sara