The 3" SP-101 in .357 mag has ben my #1 carry gun choice for a few years now. Compact, solid, controllable and very accurate. I carry mine in a Don Hume IWB holster and it is very comfortable and concealable. Geneally I carry one additional Speed Strip of ammo and I feel quite comfortable with that. On the rare occasion I feel the threat level might be higher than normal (like when protests and/or riots are planned/threatened at the Courthouse where I work) I'll jump to a higher cap auto pistol just in case but, 90% or more of the time, I'm fine with the Ruger. It's not my only carry gun but it's the one I use the most and probably trust the most.
Right before I got my SP, I had bought a shiny new Kahr MK-9 with night sights. Great little gun, but about a month after I got it my dad stumbled into this used SP for a heck of a deal ($225 in mint condition with a Galco Miami Classic shoulder rig). After shooting the SP I was so pleased with it I immediatly swapped my dad my PPK American for it and soon found myself carrying it much more than the Kahr. While the Ruger is a bit bigger, the weight was similar and I liked the idea of 5 rounds of .357 over 6 of 9mm. The Kahr sat in my safe most of the time and I eventually moved it along for something else.
My only regret was loosing the night sights but now I see Brownells has a Tritium front blade for the SP-101 listed for about $60. After doing some nightfire practice with a Trijicon equipped Glock 23 the other night I think I'm definately going to make that addition to my carry SP.