There is a new option for upgrading your seat. Seatconcepts.com
sells new foam and covers for about a dozen different bikes, specializing in dual sport types. You can do the installation yourself or send your seat to them and they'll do it for you. I've just put one on my DRZ400 and it's great. We did a 7 hour day and I was comfortable all the way.
The cost is in the $150 - $160 range + shipping for do it yourself. $20 more if they install. I send my seat pan in and had the finished seat back 7 days later.
There is much more info on ThumperTalk
Sandy & Mike Dimond