Well, in the polymer frame line the Glock takes the cake, if the 19 fits your hand, it's the one to go with...with you mentioning jeans and t-shirt wear, I take it that will mean sweat and Glocks only require minimal maintenance, and it's edges are rounded which aids in comfortable carry as well...
In the steel pistol line, the Kahr comes to mind for easy concealed carry, although with limited mag capacity and pricier mags...
Next, if single action suits you, a Browning Hi Power - but usually a little trigger work is needed to help it along which you can do yourself if you're so inclined...and then a 9mm 1911, maybe in stainless steel - capacity drops but trigger action is so nice and usually with better accuracy too. Steel guns will require a little more maintenance attention and have more weight to deal with...
Given your pistol size desire, I recommend the G19 in polymer followed by the BHP and then the 1911. BHPs are blued steel and 1911s mostly come in either blue or stainless...and of course, you can have custom finishes applied.
Holster wise, get one with a proper cant to help hide the butt of the pistol...inside or outside the waistband is your call...however, a flexible material feels much better inside the waistband - something that will form to your shape. Outside the waistband, leather still forms to your shape better ... but, if choosing the G19, Glock's own sport holster works pretty well on the cheap...
My bottom line is that of all the handguns I have, if I had to choose only one to have from now on, it'd likely be a Glock....but I'm sure thankful that I don't have to do that! ...well, not yet anyway!