Need ideas for a father/son trip I'm planning

Guys, looking for any ideas. Here is the background.

While I have a 6-year old, this is actually for a trip that I want to take with my own father (turned 79 last week). Known the man my whole life, but really don't know him, if that makes sense. He's the essential 50s-style parent: he worked his ass off, he never showed much emotion, and was an amazing father. But he just never talked much.

Only recently have stories start to pop up (usually from relatives) about how my dad's cousins were shot and killed in front of him during WWII, how he was in a Nazi labor camp at age 13, how he came over to the US after being freed during the war by British soldiers without knowing any English or having any money, etc... Just mind-blowing stuff that I never knew about.

So I thought I better get to know the man before it is too late and all I have is regrets. I'm thinking a week-long road trip somewhere in the Midwest. As I said, the man is stoic, so he doesn't really have hobbies. I have a feeling if I took him shooting, he'd do it as a favor for me, not to enjoy himself. But maybe a week of activities, such as shooting, maybe some fishing, etc would provide a lot of time to talk and learn. And by making it a road trip, that also opens up a lot of time to talk as well.

Any ideas? Anyone ever do something like this? Appreciate any and all thoughts!