With my amount of time, the coolest thing I've flown never left the ground. It was the Boeing 737-800 simulator at CAL in Houston. See b737.com for details.
My favorite airplane so far that I've flown is the Beech Sierra ( BE-24R). It's a Beech Musketeer with retractable gear and a CS prop. A little doggy on power, hard to land smoothly, but smooth in cruise and a nice,solid, comfortable airplane with good visibility.
And since the Sierra wasn't popular and not many are around, I'm glad I got to fly one.