If you commonly wear golf shirts and the like tucked in, with no outer garmet, then you'll find that full size and even compact guns are going to be hard to conceal 100% to where nobody will notice (such as if you work at a non-gun zone company and can't afford to be "made").
Then you'll be looking at something pocketable and more easily concealed, like my favorite CCW piece, the Kahr PM9, or a Kel-Tec or North American Firearms.
I've been CCWing since 1995 with various weapons and in all kinds of environs and wearing all kinds of attire. If you can wear an outergarmet or untucked shirt, then definitely carry the big gun. But even with tuckable holsters and blousy shirts, you can still see the lump under your waistband and the grip shows when you bend over or sit.
So if you need 100% concealment and to be free to dress how you like, then you'll need to be looking for a smaller gun.
Yeah, yeah, they're going to be people who come in saying I carry a .50 DE (or 1911) all day long everywhere no problem and they dress around a gun. But it's just too damn hot around here sometimes and you'd look out of place with an outergarment, making people know you're wearing it to conceal a gun (which you are.)