I didn't love the Unbroken movie either but all I heard from people who read the book is how good it was. I'll have to check it out at some point.
If you like the Lusitania book, you should check out the rest of Erik Larson's books. All he writes are historical novels but he almost writes them in a style of fiction so it's very engrossing. Isaac's Storm is about the 1905 hurricane that destroyed Galveston, Texas where the town had no warning. And Devil in the White City is about the first modern serial killer in the United States. He was targeting and killing young women in Chicago as the 1893 World Fair is happening. The book chronicles the killer as well as the city's preparation for the fair. It's one of the best books I've ever read.
The movie was just depressing! The book was not. It was full of hope, although bad things were happening!
I wouldn't like the serial killer books, but Isaac's storm sounds good!