Been flying real aircraft as a PPL since I was 18 (1983).
Am a fan of FS2004 - the graphics (especially the weather engine) are impressive (and apparently it can simulate ice buildup - not sure about carb icing though).
I use it now for VFR (yes you heard correctly) "sightseeing" using the excellent Visual Flight/Get Mapping photographic scenery and mesh for the UK (see pic below)
http://www.visualflight.co.uk/
RealAir Simulation make some lovely looking (and handling) aircraft for FS2004. These include my favourite the SIAI-Marchetti SF.260 plus Decathlon and Scout. Coming next is a Spitfire! The flight dynamics on these aircraft are the best you can "realistically" get for FS2004. The ability to simulate side-slips and spins are their main claim to fame.
http://www.realairsimulations.com/
SIAI-Marchetti SF.260 over the River Ex in Devon
Don't have much time for real flying at the moment so a few hours on the "sim" keep me happy for now.
Adam