I would spend the day having a dinner party, on Mars, no wait... on an orbital space station around Jupiter, and i would invite-
Winston Churchill (for the wit)
Bruce Dickinson (awesome singer)
Julius Ceaser (lived an interesting life)
Cleopatra (Just to see if her reputation was justified- was her nose that impressive?)
Helen of Troy (Just to see if she was a beautiful as the legend claimed)
King Arthur (self explanatory really)
Bill Bailey (he needs new material anyway)
Dara O'Brien (for the humour)
Lenin (again, pretty much self explanatory)