There are a lot of reasons to get an MBA - to the extent the intelligence of your fellow students matters, I thought I'd chime in with my observations. I've had the opportunity to interact with quite a few students from HBS, Wharton, Sloan, Stanford, and other reputable schools. My impression is that among the top 3 - HBS, Wharton, Stanford, 1/3rd of the students are would I would consider to be pretty intelligent. Another 1/3rd are okay in terms of intelligence, while another 1/3rd leave you wondering if they got in through massive donations from their parents. This ratio declines rapidly (away from intelligence) as you move down the rankings (as early as the #4 spot), at least from what I have observed.

Again, intelligence isn't everything, so I don't mean to say you should make your decision based on that. Just offering my observations in case they are at all helpful. Also, I should mention that this is all for the normal MBA programs - haven't had enough interaction with EMBA students to make a judgment.