Go with a 3" gun. SP101s are fantastic, especially with a Hogue grip. The difference in performance from 2" to 3" is pretty amazing, not only ballistic performance, but the sight radius really helps.
I tote a 3" Taurus 66, older gun I bought used at a gun show for cheap and it's a GREAT shooter. I've really come to like this revolver. It's a little heavy, over 30 ounces, but carries well. It hides well OWB with a long shirt over it even in hot weather. I like to carry it in a Hume JIT. I don't carry it 24/7, have a few pocket guns for that chore, but they don't make a .357 Revolver that I'd personally stoke with .357s for carry. The 12 ounce wonderguns ain't so wonderful when I pull the trigger. I can take some recoil, like .45-70 in a Contender, but that 12 ounce 340 Smith is ridiculous. The heft of my Taurus makes it easy to shoot well. I can say the same thing about the SP101 I had, but if I get another one, it'll be a 3"er. If you get a J frame, get a steel one. 24 ounces is kinda rough in the caliber, but it's one HECK of a lot better than 12 ounces! 3" K frames are sorta rare and expensive, but you can find the 2.5"er around. It was a quest for a 3"er that led me to the Taurus 66, a K frame sized 6 shooter. Price was right and the gun, even though it's old and has been carried and shot a lot just judging by the cosmetic wear and the wear on the back side of the Pachmeyr Gripper it had on it (from recoil), but it's a solid gun that times perfectly and has very little end shake. I'm quite happy with it. Taurus doesn't have the 3" as a 66 option anymore, don't believe. Why were there so few 3" K frames made? Of course, Smith only makes the m10 anymore.
I found a nice stainless 66 Smith some time back with a 2.5" barrel I probably should have put on my credit card, but I prefer the 3" barrels even to 2.5".