Flown too many to think of them all, but the top two have to be Kylie and Mr. Depp. (In no particular order, they're both Class A* acts)
Sean Connery has to get a special mention too - a very kind man - and Thierry Henri is always an absolute gent.
For just sheer fun, 28 days with Metallica on the Monsters of Rock tour in 1991 will take some beating (all areas backstage pass for the whole tour, and they even wangled me a pass to see AC/DC stageside, too) *and* I got a name check from Lars on MTV! \m/