Ours are adults now (21,23,25) and we last went on holiday with them all 3 years ago.
When they were younger we lived a fair way and 1/2 ferries from different parts of the family (us on an island, my family on mainland Scotland, dh's family in Northern Ireland), so in shorter school holidays we'd visit them.
Then we'd do a longer holiday in the summer, 2-3 weeks depending on where. We went to Canada to visit dhs brother and family, dh had a sabbatical when kids were small so we did 3 weeks backpacking in Central America and 3 weeks in Canada again, 3 weeks in the Dominican Republic where we did loads of snorkelling, diving, Spanish classes etc.
Also in other years we ed go to Europe - France, Spain, Croatia. But by then we'd moved off the island and still had (have) a house there so alternate years it would be 2-3 weeks there in the summer. As the kids got bigger then it was around a local music festival (growing up in the Hebrides has left all of them as avid modern Scottish folk addicts!).
This year they're all doing their own thing. Ds is going to France to visit his girlfriend's family, not sure what the girls will do yet.
We've always prioritised holidays, they're so important to us. Ds saved up 2 years ago and had a month in Australia! Dd2 is hoping to go to Vietnam if she can afford it. Dd1 has just bought a flat but still hoping for a week in the sun somewhere. Dh and I will probably go back "home" a few times, going for 2 weeks in March.