I always question the logic of those who "apply to only the top ten" or "to all of the top ten schools" etc... The fact of the matter is that as long as you do a good job in grad school, publish some work, and become known in your field, then finding a good job will not be difficult (assuming that the job market will be a lot better when we get our PhDs). The most important qualification is whether the school is a perfect fit for you. Do you like the program, the professors, the aide package, the location, your fellow graduate students, etc… Based upon those principles, I applied to two top 20s, a top 30, and a top 40. Would I have been accepted by at least one top 10 school, I am pretty certain that I would. But, those schools were not the best fit for me.
In closing, it should be noted that the most cutting edge research in my opinion, is not conducted at the top 10 schools.