The historian in me is of the "kill your idols" variety, meaning that I'd rather not meet anyone that has since deceased and was not already known to me personally because to do so would likely be a disappointment for both parties involved. There is a tendency to overly venerate those historical figures we like, and to overly demonize those we do not. To be sure, some people absolutely deserve such judgment, and to evince a pose of impartiality would be disingenuous and immoral. But most people are a complex mixture of contradictions, good deeds, and bad vices. I guess what I am saying in my characteristically pretentious and long-winded way is that I do not want to go back into time to meet anyone.
But if I were forced to choose? Maybe Christopher Hitchens or James Baldwin. Neither smoked pipe to my knowledge, but they did smoke, and are to my mind the best essayists of the 20th century and brilliant orators; so, if nothing else, the conversation would be good even if it would end up one-sided.