Real problem that is going to be face by the country when theme parks start opening up is that when you have a park that caters to a large number of out of state guests, you don't really ever get a good understanding of how many new infections were actually directly caused by the theme park. When a local movie theater opens up if it causes a spike in infections it is pretty easy to see because the overwhelming majority of people that went to the theater lived in the same area and it shows up easily and quickly... Now assume you have 2 or 3 hundred people infected in a day at a Disney park, first problem is that more than half of those infected won't even show any symptoms... then of the ones that do show symptoms they won't likely be showing them for a few days to a week. So if the guest that was infected, got infected when they first arrived for a week long vacation they might show some symptoms before they leave... but then this virus doesn't hit you with the deathbed level symptoms at the start they will initially be much more subtle. So most people infected at Disney will be back home when they really start showing signs of infection. So they go see a doctor in any of a thousand different cities around the country... Will the doctors report that they were infected at Disney? Well they won't even know if it was at Disney or somewhere along the way there in say the airplane or airport... So it becomes difficult to even know if Disney was the place of infection and unlikely that Disney would be dubbed the infection point versus a movie theater where it would be much more likely that you would have enough of a cluster in a single area that the authorities would know that theaters were a problem.
For tracing infections at an amusement park like Disney you are going to be forced to look more at the employee infection rates than the guests to see if you have a problem with opening the park. And even then using employee infections will have problems, if their workers are mostly college age then the odds of them being asymptomatic and not showing the infection goes up... and of course it is going to be much easier to protect CMs than it is guests if for no other reason than the CMs in most cases will be less mobile staying in a specific area like a cashier that doesn't move so can have a plexiglass barrier in front of him/her reducing infection chances.
In the end mass gathering places probably need to be further divided into places that are driven by locals and driven by outsiders and those driven by outsiders should probably not be opened until you have met your opening criteria across the country and not just within the state.