The GS has had the stock seat on it, and it has been ok for several hours in the saddle. However, it has not been ok for all day riding. Coming back from the MOA rally last year I got a sheepskin (rally special closeout) and it helped for the ride back, but not enough. The basic problem is pressure points, and everybody’s derriere is different. 
I started looking at custom seats from Mayer, Sargent, Russell, etc. The prices for some approached the cost of project Honda CBs, so I was hesitant. Then I came across an ad from a guy selling a Sargent seat, and after some negotiation we struck a deal. You can see from the pictures that the shape of the seats are very different. 
I put the Sargent on the bike and it seems to cradle you more. It feels more comfortable, but the stock seat seemed fine sitting on it as well. The true test is a couple tankfulls of gas, and that is not happening anytime soon given the consecutive storms dumping yards of snow in eastern PA this year. We are in the midst of another one right now…..