Garrett:
>> my own mixed emotional response to James Cameron's Titanic
I have mixed feelings about it, too. But Cameron was/is a savvy business man. He knew he had to attract the biggest, widest possible audience to recoup the enormous cost--US$200,000,000, which in 1997 was real money.
He understood that the story hook for men was spectacle, the special effects; for women, romance, the love story.
>>"truth is stranger than fiction,"
A strong selling point. So I suggest your *marketing* logline start out with "The true story of..." or something similar.
A final observation. There is saying attributed to Stalin -- yeah, comrade Joseph Stalin: "The death of a single person is a tragedy, the death of a million is a statistic."
IMHO: there is a germ of psychological insight to be gleaned from that quote. And that is, in drama, it is easier for an audience to emotionally invest in a single character, (or in a romance, two characters) than in a cast of thousands.
Can you point to one commercially or critically successful movie with a cast of hundreds, thousands where the plot focuses on more than 2 or 3, maybe 4 characters? At the moment, I can think of only one: Chernobyl. And it was a mini-series, spread over more than 5 hours, 5 episodes. (Obviously, a series gives you space-time to focus on more characters, work out more plot threads)
Even so, I think a marketable logline for Chernobyl can be narrowed down to the struggle of one character. Here's a logline I came up with: "After the nuclear power plant catastrophe at Chernobyl in April, 1986, a Russian scientist battles against incompetence, ideology and lies to contain the radiation while discovering the truth of how it happened."(32 words)
Hope this helps. As I said you have an interesting subject. Very best wishes.