I'm pretty minimalist myself in terms of material possessions so I feel that.

If you have younger kids, I'd advocate for spending on experiences. I believe that child psychologists say something like you essentially plot their quest for learning between the ages of 6-12. So taking them on adventures and developing intellectual curiosity would be the top of my list.

Now that my kids are grown, I spend on travel. I like experiencing other people, cultures, and places. I'm a firm believer in people that do very little traveling (even if it is just within the States), typically end up being misinformed and have poor viewpoints.