I fly light planes for real but it is quite expensive so I can't do it as often as I would like. With the right scenery a good plane model and a good 2rd party weather engine like ASE, which I use, FSX can get pretty immersive and very close to the real thing, probably lacking only in actual 'feel' of the controls. I can practice an approach to a real airport with various weather conditions before doing it for real. Alternatively, I can do so in places and airports around the world that I will probably never get to fly in real life. Overall, it is a very relaxing and pleasant experience. I am looking forward to what "Flight" has to offer.
Dogfighting and online coop missions with my squadmates is my other, totally different flightsimming thing. We have our good old IL-2, ROF, CLOD and other stuff for this.