The big issue for you is to find something that you'll be comfortable carrying. If it's too big/heavy, you'll end up leaving it at home.
I currently have a range of semi-auto sizes in our collection. From largest to smallest, I own a CZ 75B, a Browning Hipower, a Glock 19, a Walther PPS, and a Kel-Tec P380.
I find the 75B is pretty heavy and harder to conceal because of the longer grip. The Hipower is slightly lighter and has a shorter grip, so it carries better than the 75B. The Glock is much lighter than the Hipower, and is therefore more comfortable to carry. The PPS is thinner than the Glock, so it conceals easier under a t-shirt than the Glock. And the Kel-Tec is, of course, by far the easiest to conceal.
If I could only have one, I'd take the Glock, although the PPS and the Hipower would also be suitable "do-everything" guns.
TMann