Greenscape, in my view the most important things about carrying a concealed weapon is to have one that you are willing to CARRY ALL THE TIME, and one with which you can HIT WHAT YOU AIM AT. That may or may not be what "everybody" recommends, whether at the gun stores, in the magazines or on these forums.
You take an enormous risk of getting the wrong gun if you pick one without shooting it (or one similar to it) first. And that either gets expensive as you trade one in on another looking for the right one, or you end up with an unsatisfactory (to you) gun that you just never carry. If you don't have some friends with some different guns they will let you try, then look for a shooting range that rents guns, and try as many different candidates as you can get your hands on. See what feels good in your hands, AND SEE WHAT YOU CAN HIT WITH. They may not be the same gun.
Keep in mind when you're looking that you want something concealable. (While I agree that a Beretta 92 is a terrific weapon, most people have a pretty hard time concealing one under most clothing.) How are you going to carry it? (Shoulder holster? Belt holster outside the waistband - strong side or cross draw? Inside the waistband? Ankle?) Can you get the kind of holster you want for the gun you're looking at? Not all guns are suitable for all types of carry, and not all guns have all types of holsters available for them (or at least not at affordable prices - you can probably find somebody who will make you any kind of holster for any gun, but it wouldn't be cheap.) What kind of clothing are you going to be wearing? Business suit or Hawaiian shirt? If a suit, what happens when circumstances make you take the jacket off (temperature, business or social setting, etc.)? These kinds of considerations will affect how big a gun you will be able to conceal readily, and what kind of holster you may need to work properly with your cover garment(s).
If you don't have a lot of other guns to practice with, it will be absolutely vital that you be able to shoot what you carry - and shoot it enough to become and remain proficient with it. That means a LOT of shooting. My hand and wrist will not take the recoil of a 40 or 45 any longer, so no matter how highly-recommended those calibers may be, I simply cannot become and remain proficient with one. So they were not on my list of candidates when I chose a gun to carry. Similarly, some of the tiny, lightweight "concealment" guns make wonderful packages to carry, but can you shoot 100 rounds at a session without your hand going numb? If not, how are you going to get good with one? That's why you have to try a lot of different candidates to see what you can conceal and what you can shoot.
If you do have other guns to practice with, it would be possible to obtain and maintain some proficiency with one and carry another, although it would be highly desirable that they be of the same action type and preferably closely related (carry a compact Glock 26, for example, but practice with the larger model 17 or 19 - sights, grip angle and trigger action will all translate directly from the larger to the smaller.) Remember that if you ever do need to deploy your concealed weapon the need will be desperate, pressure will be intense, time probably will be short, and you'll probably be full of adrenaline to the point where you will not think too clearly and will more or less just have to react. That's not the time to pull out a small hard-kicking automatic with tiny sights when you've been practicing with light loads in a large revolver with target sights (to pick the worst possible example.)
Be prepared to buy several concealment holsters before you find the one that works best for you. You might get lucky and pick the right one first, but if you do you'll be in a tiny minority. I've spent almost as much on holsters as I did on the gun (which wasn't all that expensive, I admit,) although now I do have several holsters that can be used under different circumstances, so it wasn't a total loss.
Personally, I carry a Makarov, which I find easier to conceal than any of the more "standard" size 9mm Luger guns (Glock, S&W M&P, Springfield XD) and comfortable enough to shoot that I can get VERY good with it, and stay good. That's something I couldn't do with the KelTec P-11 that I had for a while, and don't think I could do with a friend's Kahr that I borrowed once, and almost certainly wouldn't be able to do with the tiny, narrow, single stack 9mms like the new Walther PPS or KelTec P9. The Makarov is not as powerful as a "real" 9mm, but it is dead-nuts reliable and I am VERY certain of hitting what I shoot at. I'll take that combination over pure power any day.
Your mileage will vary, of course, which is why you have to do your own research and experimenting. But if you do it, your are MUCH more likely to end up with a gun and holster that let you carry comfortably and are comfortable carrying.
