It's really weird. Three of my four grandparents did not exactly go out in pleasant ways. One grandfather had Alzheimer's and Parkinson's, the other broke his hip and started to have slight dementia, and one grandmother had Lou Gehrig's disease (which was probably the worst way to go). My one grandparent still alive, my grandma, drinks scotch and martinis everyday, watches CNBC and Fox News and attends church everyday.
It's really uncanny watching people you've known since childhood whom you loved just...deteriorate. But I suppose it makes things more precious and such.
When my grandfather with Alzheimer's was way gone in his mind, he would wander the halls of my grandparents' house. He was a doctor his whole life, and he would think he was at the hospital looking for his patience. One day, my grandma sat down with him and showed him a picture of him in his thirties. He had his doctor's coat on and pipe in hand. My grandma asked him, "Do you know who that is?" My grandfather paused and said, "That's one sharp lookin dude."
TL;DR Grandparents are awesome. Spend time with them