Based on data from Bama Secs, here are the states where the Division-I College Ultimate Nationals tournament has been and will be held in the 21st century.
Ohio leads as a 5-time host in Mason (2) and Columbus (3)
With 3, there's a tie between Wisconsin [Madison (2), Milwaukee (1)] and Colorado [Boulder (3)]
The only other multiple-hosting state is Washington with 2 [Seattle (1), Spokane (1)]
[Data via @bamasecs]