I have an 03. The years are pretty much the same. The RS seat is virtually useless beyond 1-2 hours. The upgraded GT seat works pretty well up to 4-5 hours. NOTE - comments made based on my butt, not yours.
I picked up a Russell during the group buy. Soooo nice during longer rides.
POI for others - I was going to get a peg lowering kit before getting the Russell seat. With the ~1"+ rise on the Russell seat, I don't think I'll need the pegs lower. You might want to consider that for your own situation.
The gas quick disconnects should be replaced as others mentioned. They are fairly easy to do. Taking all the tupperware off is the most work.
Bar backs, windshield, more tail lighting, driving lights etc. are typical add-ons. Adding the heated seat option to an RS isn't too hard or costly.
If you can get a GT for a reasonable price, consider it. I have added all the GT options to my RS except the electric windshield and leg fairing extensions. The other options have turned out to be nice to have.
Great bike, you should be happy once you get one. Good luck