Another .357 vote
Its hard to beat a medium frame .357 as a GP, do it all handgun.
As has been pointed out, ammo widely available, and power levels across the scale, w/o having to be a reloader.
A medium frame can be relatively concealable, yet still have enough size to be shootable.
My std recommendation is a 4"bbl in something like a Smith 19 or 66, or a Ruger Sec6. Stainless steel will resist the elements, and get adjustable sights to allow zero of the different loads available.