"For example, I obviously do not think Spivak and Butler are going to be sitting on my dissertation committee, but their presence at Columbia speaks to why I want to go there. They are both hugely informative in my research, so it seems silly to pretend they are not there, but I cannot figure out how to mention them without sounding like a moron. Any ideas?"
I think a simple statement of, "the presence of scholars such as x.y. and z, whose work speaks to what I am doing _______________, is a central reason for my application to this program" would suffice. Make it about you, more than about them. WHY are they a big draw for you? What about their work, specifically, speaks to your desire to work with them - a specific book or article? A class they teach? The specific comment will enhance your application; if you just mention them generally, might as well leave it out.
Also, re: rock stars and dissertations - after a decade of teaching, three year in graduate school and six years on the conference circuit talking to many of the "rock stars" and also many fine, "lesser" professors, one thing I have found to be true is, everyone is an individual, and while some rock stars cannot be bothered with anything so humdrum as advising dissertations and many rock stars however well-intentioned are too busy to really devote time and energy to their graduate students, many others consider the training of the next generation to be their most important responsibility and devote a vast amount of time to the task. And, based on my conversations with several and with their grad students, you would be very surprised at how many of the biggest names and oldest still-serving professors fall under the latter category. Best simply to take a course with the POI and evaluate that for yourself once you are in a program, in my opinion.