What is the best way for leadership to communicate high level information to a site with 500 people? (Ex. Sales revenue, progress toward site annual goals like safety and quality etc.)

Currently, we have a bi-annual event where senior management herds 250 people (they do 2 sessions) into a hotel (cost$$$$) to talk to them. There is little participation from the employees.

In previous attempts, management would try to have 15+ meetings with each group. We have people on all kinds of shifts here.