Regarding seats. I have had a number of different seats on my bricks and according to my back and ass the most consistently comfortable(I've had three of them on three different bricks) is the BMW comfort seat. Next is the Russell Day Long(had two of those on my RT).
I can and have been on my RT for 12-14 hour riding days with no pain despite a bad back on those seats. I was able to do a 24 hr/1500 mile Iron Butt run on a Russell Day Long with backrest.
On the other hand, I have found the stock bench seat to be nice for commuting and trips around town, but is too hard for anything longer than a couple hours. I don't know what model Corbin I got with my K75S, but I can barely run through a full tank of gas on the Interstate on that seat before the pain in my ass, back and shoulders become unbearable. It's a beautiful seat, but the hard surface and the riding position are just really hard on my body. It would be the first choice when I'm taking photos for a Craig's List ad to sell a bike, but it's the main reason why I would go for one of my other bikes when heading out for a ride. And the reason why it's been replaced with a comfort seat.
