Well fit and feel is going to be 100% up to you, but I have always been partial to S&W for revolvers, and I would always be looking at a .357 over a .38 mainly because of being able to have more choices for ammo...I do kinda like the Smith Night Guard, but not a budget gun at all.
I'm going to agree with Draken on most of these points. .357 even if you only plan on shooting .38 because the added length is negligible. S&W over others because they work like a clock and IMO have the most intuitive cylinder release. If you're looking for a backup carry though I'd think you'd want something with a concealed hammer and/or a slimmer cylinder like the 5 shot guns.
All that said, I personally also would recommend cross shopping with Taurus if price is a significant concern since their revolver line is for the most part a copy of S&W's.
I carry a Smith 640. The heft of the steel helps my arthritic hands control the piece. I wouldn't go lighter than the 642 Airweight, myself. Both have fully concealed hammers and carry extremely well. I'd get an older one if possible, but they're all dependable protection when push comes to bad guy.