The thin, unsupportive stock '12 SESG seat is one of the very first things I got rid of! It looks good, but the padding is far too thin, and it doesn't accommodate a rider back rest. Others here have figured out ways to have a backrest put on it, and have the padding enhanced - but I elected to just replace it. I sold it and the sissy bar to someone on here.
I have two seats - a pretty Corbin DualTour seat with orange/silver flame stitching that I use when riding solo (bought it almost new here in the Marketplace for far less than new. It's the one in my sig pic), and a Mustang Wide Vintage Super Touring seat that I use when my wife or daughter rides BSR.
I like the Corbin better for me... I have ridden all day many times on it and have never gotten sore nor numb, and barely ever even need to move around on it. The rear seat is only about 8" wide though, hard, and slants forward - so it isn't very comfortable for the BSR. They both complained that the rear seat is not very comfortable, and they tend to slide forward on it.
I bought the Mustang seat because it's very comfortable for both me and the BSR. The front is very wide and supportive, and the rear is 11" wide, is nice and cushy, and slants slightly rearward so the BSR stays planted on it comfortably without sliding forward. It's comfortable for me, but not as comfortable as the Corbin for long rides. I have found that I can ride literally all day on the Corbin with no issues at all, whereas on the Mustang I will be squirming around and need breaks. The BSRs love the Mustang though!
The nice thing about both of these seats is that they have integrated rider back rests, so it's very easy to swap them since the rider backrests remain attached to the seats, and there's nothing that remains mounted to the bike for the rider backrest. Swapping them out takes only a couple of minutes.
Ken