HappyHunter: If this is for home and not carry, and your wife already shoots your Model 10 well and likes that size revolver, go for a Model 15, which is a Model 10 with adjustable sights and have some 3 dot sights installed, if you can't order it new that way from S&W. If you can't find a Model 15, try a Model 19 - same size but will handle 357s.
Although you mentioned small frame revolvers and Greybeard provided that the Model 10 (and company) are medium size framed revolvers, I believe that S&W does not install adjustable sights on its J-frame or small frame revolvers, although you might be able to find some to fit. Or, you can go with Greybeard's suggestion for grip mounted laser sights.
OK, let's see - if you can't find a Model 15 or a 19, and if she already likes your snubby Model 10 and you can't find another to replace it, call S&W and find out how much they would charge to install a 4" bbl (comes two ways, normal tapered bbl and a heavy bbl) and 3 dot sights - you might find it about the same overall cost as the 'trade and buy' might, and they will work it over in the performance center to meet your specifications. HTH. Mikey.