A bit late to the thread...
I'm not retired - have a long ways to go, unfortunately. But I have thought about this a lot. I have wanted to move near my parents (they are mid-70s now), my sibling, and his 4 children (grown) for several years. They all live near each other and I think we miss out on so much family stuff being 7+ hours away.
My MIL, 80 y.o., is recently widowed living in a trailer park over 55 community in FL.
There is no family in FL with her. The pros are that she has a lot of activity around her. Swimming, biking, cards, dances, etc. Lots of other widows and old folk to pal around with. When she visits us, DH and I are at work, one kid is away at college, the other is in HS and busy. We try to take off time when she is in town, but only get so many vacation days a year and so we budget them carefully. We also reserve vacation days to go down to make fixes to her home and such.
My parents, OTOH, are not in a retirement community, but they have lots of church related activities and my dad is an avid golfer and has golf buddies he is out and about with a lot. Mom takes salsa and line dancing and other classes that interest her. They also are always attending family events - birthday parties with the great grandkids, football sundays with my brother and their (grown) grandsons, NASCAR tailgating, etc. My brother goes golfing or plays tennis regularly with Dad.
Having seen both options - I hope to have my parents set-up. My parents were lucky. Of there two kids, one of them moved from a high cost living area to a lower cost of living city in southern NC. They cashed out their large home equity and paid cash for a great house near my brother and his family. I hope we make it there, to. And that my kids follow. Ultimately, I'm not sure I want to be far from my kids (or one day - grandkids!)