In Region VI, our Regionals are in the fall and we have several big football schools (Michigan, Michigan State, Purdue, Indiana, Illinois, Northwestern). If Christmas/New years works for your schools, then it works for your schools. I think we prefer to give that time to our students to be with family and/or go to their respective bowl games instead
We used to do a Region Rally in the fall leading up to convention that was not well-attended. Sections 53/55 have a fall bi-sectional conference in non-regionals years for a very long time, as does Section 50, although it is more of a single-day event since the 6.5 chapters in that section are only about an hour to 1.5 hour drive from each other.
I know Region IX has a Region Rally that used to be well-attended, but I do not know since I have not been in a few years.