This reminds me of an article that used to run in one of the shooting magazines where people were asked to say who they would like to spend a days shooting with. Can't remember which magazine it was though. Most lists included their Dad.
I did get to spend time with my Dad, who I would like to have a pint with anytime were he still with us. But I didn't know either of my grandfathers. One was a farmer in Wexford, long gone before I arrived. The other worked in the brewing industry in Burton On Trent, lived in a terraced house, joined the Royal Engineers in the Great War, got gassed, survived, but passed away a year before I became a twinkle in his son's eye.
As for people who I'm not related to, I would fancy sharing a pint with Gareth Edwards, or Winston Churchill, Douglas Bader (both of whom would, I believe call a spade a spade) or perhaps Eric Clapton, especially if he brought along a guitar.