I'm pretty bony (6' and 155lbs) but I usually like the firm seats of German cars. I have no idea of why the Civic seats were so quickly uncomfortable, but they sure were. We tried a couple different cars, and it's a design issue for me.
When I felt how soft the Corolla seats were, I was convinced that I would hate them. Not sure if it's proportions or what, but I find the Corolla seats all-day comfy.
But, go back to the Recaro-made seats from my previous Mercedes 16V and Porsche 911, and they're still the best seats I've been in, period. Insanely durable/high quality leather too.