If you are considering the Ruger I'd strongly consider the 3" barrel if it is available in your area.
Reading on these boards, and experimenting at home, it seems that a 3" K-framed size gun isn't too hard to conceal. A J-frame sized gun should be pretty easy in 3" (the SP101 is roughly J-frame sized). The main concealment difference in a J-frame sized gun is for pocket carry- a 2" is much easier to conceal in a pocket as some pockets won't hold a 3" barrelled gun. However, the Ruger is heavy enough that most people can't really carry it in a pocket anyway. Thus, if you were looking at a Taurus or S&W which are lighter (especially an aluminum, titanium or scandium version) I'd say go with the 2" for the extra possibilities (pocket carry and easier ankle carry), but with the Ruger the 3" isn't going to give you any disadvantages.
As for accuracy, as they say the 2" guns aren't inherently any less accurate than a longer barrel. It is purely a human equation there- most people find the longer sight radius easier to aim accurately. Thus, you'll need to see for yourself what the difference is for you.
The biggest advantage of the 3" (in addition to greater practical accuracy for most, but not all, people) is in velocity. A .38spl, .38+P or .357mag in a 2" barrel loses a lot of velocity- enough that until some of the newest JHP designs they often had trouble expanding. A 3" barrel will give a tad more velocity and thus greater penetration, greater odds that the HP will expand, and a tad more "power".
So again, if you want the Ruger I'd probably go with a 3" if it is available in your area. The 3" is fairly rare though (comparatively anyway), and I'm not sure the advantages are great enough to special order. If all you can find in your area is the 2" then if I was you I'd go with the 2".
