Here is a solution:
1) Create view showing countd(caseid) by facility, by date.
2) Create table calculation that gets the first value of the date in the partition.
Date with the most cases = LOOKUP(MAX([Date]),FIRST())
This has to be an advanced table calculation addressing Facility/Date sorted by countd(caseid) descending, restarting every Facility:
"Results are computed along Month, Day, Year of Date (sorted descending by Distinct count of Caseid) for each Facility."
3) Then you have to filter and keep the row that has the highest number of cases.
Filter = first()==0
Use the same advanced table calculation settings.
Not sure if there is a simpler way, but this works.
Thanks -- this solution provided me with some ideas to solve some of my other 'challenges' as well!
Thanks for the guidance!