I was brought up by my grandparents and the last of them died when my eldest was 4 so didn't really have a huge chance to be around them (my Nana lived with us when the eldest was born, but had to go into a care home with dementia).
We're very lucky though with in laws.
Eldest two haven't seen their dad for 5 years, but see their grandparents regularly. Their GP's wrote to me about 8 months after their dad left us saying they knew that most of the time it's down to the parent to facilitate the relationship, but their begging of him was getting nowhere. It was a very polite thing at first, I dropped the kids off one Saturday a month. However, then I had an emergency and they properly stepped up for me and the kids. They lambasted their son (they now also haven't seen him for several years) for his shit parenting and have been amazing for the kids. They'll be at my house on Christmas Day and last year when we had a family situation they were part of the village that helped look after my younger children.
My MIL is amazing. FIL was too before he died. She now lives with us and I have a mum. She strikes a perfect balance between giving advice (but never being offended if it's not taken) and not over stepping. She sympathises when needed, never gets involved between DH and I (and the single sole time she did many years ago she was on my side!).
Both MIL and ex MIL treat the six kids in the family equally and it's been amazing - my two adult kids, DH's adult kid, our two younger kids and DN who we are kinship carers for. We're very lucky.
DH's first MIL was also a lovely lady who was incredibly kind to all of us. She died last year and we miss her terribly. I once said that the world definitely seemed determined to make up for my abusive, alcoholic parents by giving me amazing in laws.