I have heard some stories about that but I cant say what is the difference exactly. As I understood not even within the hotel management the difference wasnt so sharply put. Grand Hyatt firstly got his name just because it was built near the Grand Central Station.
Now it seems like everything about those hotels is about prestige. In Grand hotels stay people who are fancy and want to be seen. They drive Ferrari and staff.
In Park hotels stay those who really have the money and wear the cloths from famous designers and drink the best wines etc. About regency it is the place where business people stay in when on a business trip or similar. Now there is also Hyatt Place. Hope this helps.
More.
I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.