I never really gave this much thought until now: I can say with all certainly though, that I am a huge fan of pocket clips. Any discomfort or irritation I might have ever noticed from using one (which is none, thus far), is far exceeded by the supreme usefulness and convenience of it; the knife is right where I need it, and in the same position, every time. No fumbling, no mixing it up with anything else in my pocket, no scratches. Perfect.
As others have mentioned, if your pants have belt loops (I'm guessing they do?), put your keys on a carabiner, clip it to one of your rear belt loops and tuck 'em in your back pocket (mine grab a ride in the same pocket as my wallet). Best idea for keys, ever. Now your knife can cruise solo in your front pocket (although I sometimes have a lip balm stick or change in there, too).
Honestly, I very likely wouldn't carry a knife daily if it didn't have a clip, so... I guess that about sums it up for me.