I've openly carried a fixed-blade here in urban San Diego for several years now. I normally ride a motorcycle, so having a knife hanging from my belt on my side isn't an issue as far as comfort. My sheath is designed for quick removal from my belt (the top of the the belt loop has heavy duty snaps), so on the rare occasion I drive or ride in a car, I remove the sheath, then attach it when I get out.
I have to be conscious of how and where I sit in places like restaurants. Either I sit in a chair, or I sit on the end of a booth with my knife facing out (so it doesn't dig into the booth).
Aside from the issues of sitting, I wouldn't even know the knife is there.
When I first started carrying a fixed-blade I was concerned about peoples reactions, but it's been eight or nine years now of daily carry in public and not one person has ever said a negative word about it. I also haven't noticed any sort of negative reactions like weird looks or whispered comments, but I don't look for such reactions. No one has ever called the cops on me, and no one has ever asked me to leave their business. These days, carrying a fixed-blade seems as normal to me as wearing shoes.
I've seen more than a few people openly carrying fixed-blades here in urban San Diego, from fellow bikers, to average joe's, and even clean-cut college-looking guys. One of the most memorable guys I've seen carrying was a young guy (fellow customer at a Mexican restaurant). He was in his late teens or early twenties, clean shaven, short, perfectly combed hair, light blue polo shirt, kahki pants. I'm not sure exactly what the knife was, but it was hanging upside-down from his belt in some sort of plastic quick-release sheath. I think it might have been a CRKT Hammond ABS Operators knife.