Both my wife and I are getting up there in years and my 2012 G37 Coupe's seats are too hard/firm. I've tried several cushions, which do help some, but still longer trips become painful (hip issues, mostly).

I was wondering if anyone has tried any aftermarket seats that are much cushier/comfortable than these hard stock seats. I enjoy driving my G37 but, lately, have started to consider getting rid of it due to this issue.

Thanks in advance!!!

The aftermarket tends toward sporty/racy and not comfy, but fitting aftermarket seat frames always comes with its own set of problems, often very ugly ones. You'll probably be better served to find a good motorcycle upholsterer and let him rework your cushions with better materials. Most of the old timers in the motorcycle seat biz have forgotten more about cushion comfort than the whole rest of the industry ever knew. The best ones I know about are these guys:
https://www.meancitycycles.com/

Just an aside, the best seats I personally ever sat in were Peugeot 304's. The cars were complete euro-crap, but damn, those seats were wonderful!