I had the same experience when I got my 650 five years ago. I was fine on my half hour commute to work and back everyday, but after an hour on the bike my butt would be completely numb when I stood up.
Before you get sucked into the vortex of everyone's personal experience with the many after markets seats out there, understand one thing: just like everyone wears different clothes, and helmets and boots, and different bikes are good for different people, there is no single magical seat that will be comfortable for everyone.
I used the DIY website that NorthernRider linked to, and greatly improved the stock seat on my 650. The biggest improvement was carving a V groove right down the middle of the seat for my tailbone. Second to that I added about 6" of 3/8" closed cell foam to the front of the seat (the point by the tank) which effectively tilted the angle of the surface back just a bit. It stopped me from sliding forward into the gastank on every freaking little bump in the road.
Im happy with my two minor mods to my stock seat. I might pull the cover off again and put in a layer of gel pad someday, but for now I can ride the bike for an hour to 90 minutes, get off and stretch my legs, and ride another hour.
For me the other thing that makes the bike more comfortable for longer rides is a 'drivers' backrest. Having even a little bit of support in the small of your back makes it easier for me to sit up straight, and not feel like I riding on a bar stool.
Couple things about the DIY website: shaping your foam with a 4.5" angle grinder sounds insane, but it works incredibly well. Just have to be careful, only sweep the grinder in one direction (like you are spreading butter dragging the wheel across it, not carving a turkey with the leading edge!)
One thing I did differently, instead of putting the seat cover back on with a powered stapler, I got a box of 3/8" sheet metal screws (I think #6) and washers and used those to put the original cover back on.
Like others have said, you can get another OEM used seat pretty cheap, so dont be afraid to take the cover off your seat, and at least try the V groove for your tail bone.