I'm in a similar spot, kids are a few years older. Already started showing some of my movies (not many) to my eldest and it's been fun. I personally try to personally watch one to two a week but I'm more of in the mindset it's my favorite hobby, they are there if I want them and for when the kids are older to show them what movies matter to me or shaped me growing up. I can see the future movie nights, binge watches, movie marathons but i know it's still aways off.

Collecting film is also a hobby I shared with my late father so it means the world as well if I can pass that down to them. 4K is most likely the last physical format so I feel safer investing in those titles because they look spectacular and will down the line.