Per this link, the team ranked the overall #1 seed has the opportunity to select its preferred first and second round site and preferred region:
If UCONN isn't the #1 overall, is there any coach or AD sick enough or affraid enough to pick the Brooklyn and the East to spite UCONN?
How the field of 68 DI men’s teams is picked for March Madness
The NCAA’s guide to how the 68 teams are chosen, seeded and bracketed for the Division I men's basketball tournament every season.
www.ncaa.com