Damn this is hard.
Men:
Barry Sheene (RIP) - two time world motorcyle champion, legend, playboy, comedian and all round good guy.
As for the non-dead guy.... I dont know maybe Valentino Rossi (todays Barry Sheene), he may even bring along one of his model girlfriends!
Women:
Marilyn Monroe (RIP) - aside from the obvious reasons, whilist on the island I would write an authorised tell all auto-biography so that should I ever get my fat ass of the island I'd become filthy stinking rich (instead of just filthy and stinking).
And yeah Kylie Minouge would be an interseting prospect. Maybe NIgella Lawson or whaterver her name is so she can cook me dinner