Bret,
On my Sherpa I use the Airhawk for long trips - it's a necessary evil. The bench seat on that bike is atrocious.
On the Monster I have a DP Gel seat and it's great. Not so great for the pillion, but hey, they can always bike themselves their own bike ?! or you may just need to massage their buttocks at the end of the day!
only females as pillions of course!