One of my most favorite things to do was take the Cessna Grand Caravan and try to pancake it down on the smallest, most difficult runways I could find. Lukla and the surrounding area was a favorite hotspot for hot-chit bush pilot types. Lot's of great runways in Alaska/Canada as well.
Of course the other half of the fun was getting back out again.

Man, I should get a copy of FSX going again.
EDIT: Another thing I liked to do was take the Extra and start at the north end of the Grand Canyon and fly NOE all the way to Hoover Dam. Then there was that around the world flight I did in the Lear... oh man it took a couple weeks but was awesome. Some of the most rewarding stuff was winging with r/l pilots. Listening to the professional manner with which they communicated to ATC was cool as heck.
And the lobby... oh man the lobby was un-moderated, so there were some wickedly awesome flame wars.

I remember when that Air France flight went down off of South America. The FSX community had the case solved within hours. Of course it was all speculation at the time, but the general consensus turned out to be true.
I could go on and on about the awesomeness of FSX and it's community back in the day.