I have been sticking to a "depth over breadth" strategy in these 500 word Goals essays. Not only is this an easy way to manage the length of your response, but it allows you to focus (perhaps illustrating with a fun story) on WHAT EXACTLY makes the specific program attractive to you (which is necessarily related to your stated goals) and WHAT EXACTLY about your personal/professional experiences will be additive to the MBA adventure of your classmates.
These may only be one or two facets of the program and/or your background, but I think it makes more sense to hone your case on what is most compelling rather than create a shallow laundry list of qualities that you feel obligated to mention, devoting only a few sentences to each. These "attractive traits" (extracurriculars, leadership training seminars, alumni networks) are likely strong at ANY top 15 school. Mentioning that you plan to join the Jousting Enthusiasts Society as part of a weak-sauce-obligatory-paragraph-on-extracurriculars-that-you-shove-in-right before-the-conclusion-so-you-appear-well-rounded says squat. If joining the Jousting Enthusiasts is that important to you, make it your whole essay. Tell them from soup to nuts how it relates to your career goals of starting a rondel-manufacturing firm, past experience slaying dragons at Renaissance Fairs, and, most importantly, WHAT YOU CAN ADD to the program in terms of innovative sword combat techniques.
To emphasize, if your other essays/resume/activities divulge that you are a Sonics season ticketholder who played D-1 college basketball and has been on some form of organized hoop team since age three, IT IS SIMPLY GRATUITOUS TO MENTION (as a side paragraph) IN THE GOALS ESSAY THAT YOU PLAN TO JOIN THE BASKETBALL CLUB.
I could be wrong and my essays could suck b/c of lack of breadth, but that's the chance I've taken. I'd be interested to hear the thoughts of others on this.