I'm going to tell you something weird but true. On the inside, an old person still feels like the young person they used to be. How old you feel right now...that's how you will still feel on the inside when you are 78 years old. They aren't interested in "old people stuff." They are still interested in whatever that particular person has been interested in for all their life.
In my case, that happens to be science fiction movies about creatures that chase and kill people. So I loved Jurrasic Park, Aliens, Alien vs Predator, The Thing. I have really liked the Planet of the Apes reboot in recent years, and am looking forward to the next one of those movies in 2017.
I also like silly movies. I liked Guardians of the Galaxy because it was silly and especially because it had a lot of 70's music in it, which I loved when I was young. So I would probably like the sequel that's in theaters now.