For PD, a hammerless is fine - you will only use a PD firearm DA anyway. As for 'trigger jobs', do a simple one yourself - involving nothing more than a little aerosol cleaner/lube and your trigger finger. Most S&W's come fresh from the production line and testing with their innards as dry as the Sahara. Sometimes, some manufacturing grime finds it's way into the innards as well. Some serious blasts with the straw on your aerosol cleaner can's nozzle, and RemOil or Breakfree are fine, through all orifices - for a longer time should some crud exit the lower openings. Shake as much out as possible, with the revolver wrapped in a paper towel. Dry the surfaces as much as possible.
Make sure your ammo is put up somewhere. Double check your cylinder to be sure the chambers are empty. Settle down in front of the tube with a useless program to view - and start dry-firing away. You must dry fire at least 1,000 times - switch hands periodically. You are 'wearing in' the new surfaces - removing burrs, etc, by dry firing. A good trigger job simply replicates thousands of trigger pulls. Do it yourself... you'll build up your trigger finger, too!
If you opt for a commercial trigger job, stay away from a hammer spring change in a PD revolver. Sure, most reduced power springs will ignite nearly all primers, but what if the one in a thousand that won't fire costs you your life? My plinkers have lowered power springs, my CCW/PD are stock. Do find a comfortable set of grips or stocks. My wife likes slick wood with no checkering and softened finger grooves. I resanded and refinished some goncalo alves Hoque stocks on the 3" 65 she uses - my poor-man's 65LS. She practises with some wimpy .357 Magnum 158gr LSWC homebrews, but has 158gr LSWCHP +P .38's aboard and in the speedloaders for 'effect'. Those old 'FBI Loads' still enjoy a 6-8% higher 'OSS' (one shot stop) rating than my longtime favorite, 230gr FMJ .45ACP. Hope this helps.
Stainz
PS Consider the 642 with some larger grips of your choice... you can easily replace it should you have to.