If you like WWI history, I certainly second the previous suggestions - Blueprint for Armageddon and They Shall Not Grow Old.
But there's a fantastic youtube channel I recommend as well:
https://www.youtube.com/user/TheGreatWar
Literally hundreds of hours of content - really cool channel with some shorter videos and longer ones depending on the amount of time you have. And obviously you need to go to the Museum at the Liberty memorial.
Ultimately I wanted to be super-stoked for this movie but the first trailer left me pretty underwhelmed. I'm hoping that some later ones will look better.
And to be clear, I'm not sure WHY I didn't get fired up about that because I feel like I should've been. It just didn't get me as excited to see the movie as I thought it might.