Although I mentioned the consortium programs for Emory & UMass, I realize I didn’t mention the opportunities available at UPitt, GW, and Brandeis.
Brandeis: Has cross-registration opportunities with Babson, Bentley, Olin, Wellesley, and then the arts & sciences colleges of Tufts, BU, and BC.
https://www.brandeis.edu/registrar/registration/cross-registration.html
GW: Has cross-registration with all the D.C. schools (including Georgetown) and other very nearby colleges, like U. of Maryland - College Park.
Pitt: Has cross-registration with other Pittsburgh schools, including CMU and Duquesne.