This is another good point-

when looking around for a CFI job, my guess would be that you would want to pick a school that has several airplanes, not just one or two- because at any given time airplanes will be down for one reason or another (maintenance, 100 hr, annual, oil changes, etc etc). And if the school has a high flow of students, the planes will be down ever more often due to increased wear and tear and need for maintenance. IMO, the best bet is to pick a big school with a good size fleet of planes.