I have a 97 road king..looking to upgrade the seat. Have checked out a couple from mustang (regal) and the HD sundowner. Opinions on either one from anyone that has one or has had both? Looking for comfort on longer rides especially for passenger.

 

I've got a Sundowner, both the lady and I are happy with. It took 500-1000 miles to break in to the point I was satisfied with it, but for my wife it was an instant upgrade to the stock. We haven't done any full day rides yet, but we've done 380 in a day and 1250 in 4 days and I've heard no complaints.

edit to add - I plan to send it to mean city cycles this winter for a mod. I want to have it shaved down and narrowed a bit. At first i was thinking I'd do the memory foam mod...but now that I'm used to it I'm happy with how it feels. That being said, I only have a 31" inseam, and the stock 2011 flhrc is a little high for me to begin with, I'm not blaming it on the seat.

 

11'RKC here with the Sundowner for passenger comfort.
Big difference if you look at them side by side.
Sent it later to Mean City Cycle for the memory foam upgrade, and super narrow to reduce the spread and feel better planted at slanted stops or whatever, 32" inseam. Very nice.
All a part of making the bike fit you - and keeping the little lady happy, of course.
Face it - several hours in the saddle; Why be miserable?
BTW - most dealers have demo seats, go try one on for a ride...