I will go with Ironraven and recommend a revolver, but would suggest a 357 magnum with a 4" barrel and adjustable sights. Here's my reasoning.

You said you were a bigger fellow, and so should be able to handle 357 magnum loads okay, with practice. That being said, you can start out with good 38 special loads, which can be an effective self defense round just as any 9mm could. I lean toward a revolver because of simplicity and durability in general. Any decent model will take a fair amount of abuse, and the operation is as intuitive as it gets. As your proficiency and comfort with the weapon improve over time, you will be able to take greater advantage of the additional capabilities.

I've toted all kinds of pistols concealed, from a little Grendel 380 pocket pistol up to a Ruger Super Blackhawk 44 magnum. My two most preferential carry pistols were my Glock model 21 in 45 acp, and my Dan Wesson 357 mag with a 4 inch barrel. Neither one was any more difficult to conceal. Those little 22 mag pocket revolvers are too tiny for me.

As with the rest of the folks here, the holster will make or break the deal.