Best mod so far is my new seat from seat concepts.
I am 5"10' 220lb. Not tall.
went from bmw LOW seat to seat concepts TALL seat, standard foam, grip surface.
Difference is amazing. The low seat was uncomfortable after a short ride and my knees got sore with being bent too much. I did a 690km (430 mile) round trip last weekend. Plenty of stops etc, but still pretty good.
I had an air hawk on my old R1200gs. That was pretty good. But this seat, on the f800gs, is better for me.
The tall seat means that it slopes up towards the front, which is more comfortable. I am on tiptoe when stopping, but I don't mind that. My last bike was x-challenge, so used to it. When you are going it is great.
The seat is flat so I can move back and forward on a long ride.
I do not like the grip surface myself as I prefer to be able to move about. However as I do take a pillion, I chose this so that my wife does not slide into me every time I brake.
Great value for money. I thoroughly recommend it.