Re: glock 21
I'm 6'4" 235lbs and the G21 is BIG. I love the gun for camping and range work, but it is not a CCW. Like Chris Rock says "I can drive a car with my feet, but that doesn't mean it's meant to be done". I had the G30 and it's just as thick, just shorter, still not ideal.
If you really want a .45 for CCW, look at the new XDS or a Glock 36. A single stack is about the only way a .45 is concealable w/o going overboard with the dress code. There are people that do it everyday, so don't let me sway you. I just think there are better options in a belt-side carry (1911) or single stack striker fire or DA.
I fully endorse getting a G21 as they are fantastic guns, I just wouldn't CCW it.
Just my .02