When getting into the size of the Thunder, PPK and even the p232, you might as well go with a 9mm. There are a lot of great 9mm that size or even smaller. Bigger, cheaper and more abundant ammo (not so cheap now and abundant now).
The reason why I picked the .380 ACP was because of the true size of a pocket pistol. Overall length for a pocket pistol should be no more then 5.5" IMO. Anything bigger then that a is bit of a hassle to carry in a pocket especially in a pocket holster. This is just my opinion so please do not get offended.