For about 15+ years, I've used an Alaska Sheepskin seat cover, first on my BMW RT, now on my RT-S. It does OK for most rides. For a while, I experimented with a layer of bubble wrap under the sheepskin. Yep, it works, somewhat. Adds a few more hours of tolerance.

I looked into Ultimate seats. I see a big drawback in that they recommend a rain cover if riding in the rain or parked in the rain. It's bad enough that I have to do the roadside chicken dance to get into my rain suit; now I also have to fuss about putting on a seat cover?