All I can say is the BT private hire day back in the early 2000's was the best day both I & many other [Alton Towers] staff had whilst working there.
Basically the visitor profile demographic changed completely. The park was busy - but queues were short, as the visitor profile had changed. You had to have been working at BT for at least 20yrs to get an invite, so this put parents at a certain age where most were uninterested in a lot of the rides - they say on the main lawns enjoying the entertainment. As at least one parent had been with BT for 20yrs, this put their children at a certain age (generally late teens at least) so there was zero trouble. Queues were short / non-existent. Atmosphere was great. The litter pickers even had guests picking up litter with their hands and putting it in their litter bags.
As one staff member said... "amazing what a difference it makes when you only let people in who have worked for a living for years".
The only thing BT got wrong was mobile phone reception. 99% of attendees on that day were on Cellnet and no additional temporary capacity was added. Yes, you'd get a signal, but don't try making or receiving a call as it would fail.