I ordered the iPhone 6 Plus and get it tomorrow. I also ordered a case for it and am looking at it right now. I've been holding it and playing with it and I gotta tell you, I really like the size it turns out (I was sure I'd want the 6 and that I was going to exchange it).
So here's what I'm going to do: I'm going to order Apple Care and then use the phone as I normally would, for up to 2 years. If nothing goes wrong, great. If it warps, I get a new phone, and I demand that I don't pay a cent for it since it will be used the way it should be. I'll use a slim-ish case, cause I always have, always will.
I've had a 4S the last few years and am one of those "idiots" who wears it in my back pocket half the time that I'm on foot, at least during warmer weather when I don't have a jacket with the bigger pockets on me. I don't know why I prefer the back pocket but I think it's cause it looks better on me that way (I don't want the bulk in my front I guess?!). But when I get in the car, I habitually take it out so I can see and hear it better or charge it etc. So I don't sit on it although on occasion I forget to take it out and it's down low but not under me or not far under me anyway, between me and the back of my seat - not so far that it could or has ever hurt it. Again, it's the 4S though - MUCH more durable phone, and it's never bent even a little.
In the meantime who knows - maybe they'll recall them (?). Probably not. But I really like the size of the 6+ in my hands!
p.s. I guess I'll be your back pocket guinea pig, when it fits. I'll put a case on it and use it as I usually do, which is to wear it in the back some of the time (when with a jacket) but not sit on it. I'll make a point to always remove it before sitting, or it won't count.