Haha, I'm not trying to do any crazy endurance racing. Just want to be able to ride for more than a couple of hours without feeling like a mule kicked me in the rear.

MONKEY BUTT! - Books

Monkey Butt. It's a good read.

TNC stated it well. And I'm not against gettin a comfier seat, but.....
Compared to a "real" dirt bike the klx seat feels like a lazy-boy. You guys calling it a 2x4 should try a KTM seat. :D
For what its worth , I remember riding around all day on my bmx bike sitting on one of these hard plastic seats.

http://www.bmxsociety.com/uploads/mo...747560457.jpeg

Hard seat
 

I think you may get used to the seat, however maybe the previous owner was a heavy lad and has the preload set too tight for your weight.
If the suspension is incorrect for you it could be an unreasonably firm ride.

Generally the bike should drop 3 to 4 inches when you sit on it, with your feet on the pegs. If your bike only drops two to three inches or less, then that could be why you get a firm ride.

You can measure sag, it helps to have a friend to help...

Pop the bike up on a mx lift, or somehow, to take the weight right off the back wheel, clean up top of the monoshock a bit, and give the shock adjuster and lock ring a spray of WD40 or other penetrating oil.

Slacken off the preload just a couple of 360 turns and measure again. Retighten the lock ring when finished. If you have access to special tools fine, otherwise I think the following is OK, but try not chip the spring's paint.
Adjusting the suspension for different track conditions etc. requires knowledge and experience, but this is a good start.

I think the KLX broke me in for the KTM seat, I find them both fine off road. Of course I'm off it most of the time.

On the road, I break out the sheep skin.

I comfortized my seat without paying for a new saddle. I'm 5'8" and I wanted a little more 'foot to ground' if you will. In the process, it widened the seat and made a substantial difference. I haven't had the pleasure of a Seat Concepts saddle, but at this point I don't necessarily need it.

https://www.kawasakiforums.com/forum...ed-seat-39700/