In reply to Removed Userwaitout:
As others mentioned, Vonnegut and Orwell come to mind, and I guess for the same sort of reasons I'd also choose Aldous Huxley. I think they'd help us understand what kind of a beast our modern society actually is, and where we are / might be heading for.
Some other people that might be able to use their skills to help us think about the world today and see ways forward, maybe David Hume and John Stuart Mill.
Also I'd love to see what historic politicians would make of the UK and the world today, eg JFK, William Pitt the younger, William Gladstone, then going further back Emperor Justinian, Marcus Aurelius, Julius Caesar, etc... In some ways maybe the older ones would have less to offer than the more recent ones just because the world has changed so much that its hard to imagine whether what made them interesting and successful back in the day would be relevant in today's world. But then again it would still be interesting just to hear them try to get to grips with things and what they make of it coming from such a different background.
Also not that she's dead, but I'd love to know what the Queen is really thinking. I imagine there are few other people around who have met so many public figures, been privy to politics at the highest level for decades, and communicated with so many influential people on all manner of topics.