The 4 inch barrel is the more versatile barrel length. I am with others that a 4" S&W 686 would be a good choice. I have carried as a duty weapon when doing private security and have carried it concealed when working plain clothes. I have also carried it and a 4" Colt Python in the same holster (not at the same time) when off duty now that I am a police officer. I find that both conceal very well for me. The 686 will handle any factory 357 load on the market and ask for more. Since you also mentioned laser sights, you could check out the line of lasers from Crimson Trace. They are made in the gun's grips.
