With the possible exception of Darden, I haven't heard about a big discrepancy in the workload at the top schools. Slight differences would be practically impossible to measure, especially since there are going to be elective options that require different levels of work within the same program. I can appreciate not wanting to choose a school with a significantly bigger workload than average, but I kind of agree with matador that I wouldn't make a $100k decision over that alone when the differences aren't huge and there are so many other factors that determine fit.
Overall, it seems like every program has plenty of time for socializing (especially if you don't have a significant other or other obligations outside of school). The people I know from Anderson who were completely swamped were the ones who took on a ton of leadership in clubs and organizations. Even they managed to pack in a bunch of social stuff. Those that mostly just went to class and did recruiting seemed to have a good amount of free time on their hands. I had a roommate who was at Marshall as well and would say the same about that program. The degree to which academics are challenging for you in general, and how important you think grades are will also play a huge role, of course.
There's some discussion about how busy b-school is here: so-how-busy-will-i-be-at-b-school-107482.html?hilit=how%20busy
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