I suppose if you live in New York where they are now lowering the magazine capacity to 7 rounds it is rather pointless to argue for the greater capacity a 9mm would give you. You might as well have a revolver.
I would still like to push you towards a semi-auto just because they are faster to reload (which would help deal with the ludicrously small magazine capacity), easier to shoot (no DA trigger to help pull your front sight off-target and less recoil), and the ammo is normally easier to come by and cheaper than .38 special or .357 magnum.
But, you said the gun won't be for defense. So, I say get a .357 magnum 4" or 6". It will be fun to shoot and you can save money by shooting .38 special and only shooting .357 magnum when you want to have maximum fun. Again, this gun isn't for defense so any .357 magnum 4" or 6" revolver will do.
Just to get something different you could get the Chiappa Rhino 4" revolver. Its ugly, but the chamber that fires is the bottom chamber instead of the top chamber which directs more of the recoil into your arm and gives you less muzzle flip. It will make shooting .38 special really really fun, easy, and fast. Unfortunately it will probably direct more of the .357 magnum recoil into your hand/wrist/arm. But that is why you are shooting the .357m right? Because its fun to feel the boom?
Rifle: Custom AR-15, Tavor, Arsenal SGL 31-68
Pistols: Colt Python, XD(M) 4.5" .40, Glock 19, M&P 9mm, Walther PPQ 9mm, HK P30S 9mm, Walther PPS 9mm, Browning Buck Mark