I will add to the chorus recommeding a 642. Mine is actually an M460, which was a 642 given a certain package of work by the Performance Center back when every little variant seemed to get its own model designation. (That was not a typo! Yes, today's 460 is a monster X-frame. S&W sometimes does re-use model numbers.)
I do NOT think the Air-lites, with titanium cylinders, are a good idea, at least for my hands. Airweight is light enough for me. I sold my AirLight Model 342, as it was past the point of diminishing returns.
My actual present secondary/tertiary gun, for concealment when in uniform, is a Ruger SP101 in a Kramer horsehide/kydex pocket holster, in a cargo pocket. (VertX pants) This may change, as we are switching uniform cargo pants, and it takes a seriously sturdy and large pocket to accomodate such a large and heavy snubby. I may have to revert to ankle carry if I want to keep toting the SP101, or may go back to using the J-frame.