I do find myself putting it in my back pocket more....never really did that before this phone. It fits in my front pocket fine, but I find the back more comfortable. With the strength of stainless steel, I'm not particularly worried about any breaking/bending. This is my first phablet.
Years ago I developed a pain in my thigh while driving that was traced to sitting on a large wallet in my right side back pocket. So I would definitely not be sitting on it, in any case. I've also minimized my wallet contents. Obviously, the cell phone size explosion is being privately funded by orthopedics and chiropractors who are going to get rich on our desire to carry large phones.
I use a holster on my belt. Maybe because I spent so long in the military carrying gear on the belt. I know some don't think that is cool but I have never tried for that appellation.
I have use both my front and back pockets but always take it out before sitting. As for driving, I use a cradle in my car for all my phones.
Do you happen to use one of those magnetic cradles? I'm intrigued by them, but can't help but feel that strong magnets might not play nice with expensive electronics.