I'll admit right up front that I do NOT have any experience with the cushy seats etc and I still run a stock '10 SESG on my '09 SERG.
But I can relate my experience in street rodding. I think it may be relevant.
In my '40 Willys coupe I bought a new Glide bench seat and it came with a foam kit for the upholstery. When I first sat on the foam with a towel over it there was this great feeling of softness and comfort. I had the interior done in red leather, black street rods have to have a red interior, it's an unwritten rule...

So on short trips it was great. Then I had the chance to be part of Rod & Customer Ego Rama Shootout. I lived in Michigan and we were to all meet in Wendover UT right next to the Bonneville Salt Flats.
By the time we drove to Bonneville, my butt was starting to hurt. I continued to drive for a total of 6300 miles in 23 days and by the time I was home my butt was REALLY sore. While on the shootout I got some advice from an older rodder, George Poteet, some of you have probably heard of ole George. He knew exactly my problem and gave me a suggestion and boy did it work.
The problem was that my seat felt great and it was soft. But the seat began pinching my butt and legs because of the softness. George told me that on every Glide seat he has installed in his cars, he takes additional foam and builds up under the seat springs to add more stiffness to the seat. So in this case when I did that the seat felt a lot firmer and still with a little give. I didn't sink down into it as I used to. I went on another couple thousand mile run and I didn't have the sore butt like before.
So I'm thinking that on bikes you can probably go TOO soft and your butt and private parts are going to be pinched. I've found out that a good fitting firmer seat gives me more long haul comfort than a soft feeling seat short term.
I'm afraid that with memory foam or thicker gels, one might get too much padding and cause issues.
Come to think about it, my Mustang seat on my '76 FL is quite firm and at first I thought it was too hard. But over the years of riding this thing, I've found it to be very comfortable because of the firmness.
So that advice and $.50 will by you a soda from our machine.
Good luck with your seat choices.