Clumping is a valid strategy, but I don't find your clumps to be geographically sound. How is flying to Richmond and driving an hour to UVa different from flying to Syracuse and driving an hour to Cornell? Why is flying to Chicago and driving 2½ hours to South Bend easier than flying to Boston and driving 2½ hours to Dartmouth? Red Hook is taxicab distance from Rhinebeck, which has a dozen Amtrak trains from New York every weekday.

I would try to pick a set of fewer but more diverse institutions, based on criteria you want to test. As different as Penn and Columbia are, for example, they are both big universities in urban environments in the Northeast, and the student experience will be much more similar compared as opposed to a Miami or Dartmouth (in the same way that as much as Boston and New York or Los Angeles and San Francisco have a rivalry, they are much more similar to each other than they are to Albany or Fresno).

These alternative clumps might be

• Northeast, South, Midwest, (no Western schools?)
• Metropolis, city, small town
• Urban campus, suburban campus, rural campus
• Big school, small school