Is the Houston school an official school or an FBO? If it is a school, you will have students given to you, if you are at an FBO you will probably have to find your own students. you will definately fly more in Houston, but when I went to my first job interview, they were impressed with the actual instrument time I had, because I got lucky and had several linstrument students which keeps the schedule busy even on bad days. I guess my decision would depend on student load in Detroit, and like another poster said the possibility of multi time.