One of the best passenger seats is the Russell Day Long. Most of the production seats offer good driver seats but the passenger is an afterthought. It is obvious the driver and passenger seats are very different. With the Russell the passenger seat is given the same level of refinement as the driver. For both riders you send in your height, weight, waist, inseam, and a couple pics in a typical riding position and feet down at a stop, along with any special requests. They build the seats from the stock pans to match you AND your passenger's dimensions. You choose the seat material(s), color, stitch pattern, backrest, heat... Both seats have a steel suspension system under the wings to match your weight. Cost is quite comparable to an Ultimate setup. I had an Ultimate on the X, great for me, barely acceptable for the passenger on anything other than day rides. Both the front and rear Russell on my GS is very comfortable for any distance.
https://www.day-long.com/gallery_Honda.html
My 650GS Russell seat, dual setup, light gray vinyl, half moon stitch pattern, no backrests, no heat. Passenger seat is slightly smaller than driver because it is a 135lb seat vs 190lb driver. Also had them move me closer to the bars and a little higher to relieve the knees a little.