There have been a lot of good points and I see you're looking to go 686 or one of the heavier revolvers.
Carrying a heavier gun really isn't that bad, my EDC is a Speed Six and it weighs about 2 lbs even so a little heavier than the SP101. The trick is getting a good belt and a good holster, it really makes a huge difference. You'll notice the weight for about a week then you get used to it, I forget it's even there sometimes.
As someone else mentioned grips can be a huge difference maker too. With revolvers the grip absolutely has to fit my hand, especially with 357 magnum and up. With semi autos I can usually adjust and make it work but revolvers are a different story. Now if we're talking a 22 or light 38 target loads or even 38 +p loads in a heavier gun then grips aren't a big deal. I would try some different grips on the wife's SP101 before you make a decision. What works for one person may not work for another, unfortunately I'm not seeing too many options for the SP101. If it were me I'd try the Hogue monogrip (not the nylon or wood versions just rubber) and the Pachmayrs. Pachmayr has the Compac and Diamond Pro for the SP101.
I don't have an SP101 and I haven't had the chance to shoot one yet so I can't make a specific reccomendation on a particular set of grips. All I can say is go with rubber and try a few until you find what works. Wood grips are ok on a heavier gun but even then I prefer rubber. I had an early model low back Security Six 4 inch and the factory stocks would beat my hand up like I owed em money, I found a way to make a set of Pachmayrs for the more common high back frame fit and they turned it into a whole new gun.
As for bigger heavier guns you got some options. I prefer fixed sights on my carry guns but adjustable sights aren't a deal breaker. They're out of production now but my number one pick is the Speed Six with 2.75" barrel. They made some with full 3 inch barrels but they're kind of rare, definitely not as common as the 2.75s. There's also the Police Service Six which is basically the same gun but with a square butt frame instead of a round butt but the short barrel Speed Six is easier to find. If adjustable sights are your thing there's a 2.75 Security Six too. I'd try to find a heavy barrel version if you go with one of the Sixes.
Then there's the 3 inch fixed sight GP100 which may just be what you're looking for. Since were talking a woods guns concealment may not be your top priority and the extra weight will help with recoil further. The SP101 is 27 oz, the Speed Six is 32 and the GP is 36. There's also the K frame Smiths and they're the same size/weight as the Sixes. For me the Sixes are the sweet spot, small enough to conceal yet big/heavy enough to control full power magnums.
The shorter barrels are going to have more blast and flash than a 4 inch or a longer barrel and they might have a tad more recoil but the added weight is still going to help. You could try tailoring the load to the gun too, if bears aren't a concern Double Tap makes a 158 grain hard cast 38+p load thats perfect for smaller guns. Its not 38/44 level like the Underwood or Buffalo Bore versions. If you reload then that gives you even more options.
