MANY good suggestions above. For me, what helped a lot is the Air-Hawk air cushion. I also like to stop frequently and walk and stretch as many have suggested. I think age also plays an important factor. As your bones get older, you're simply not going to feel comfortable doing as many miles/day that you once could, no matter how often you stop and stretch.

Here is a good article on this subject of comfort while riding. Many in this thread have already mentioned some of the suggestions in the article.

https://rideapart.com/articles/stay-...torcycle-rides