+++ on going to a range that rents handguns and trying a bunch before forming an opinion of what YOU would like. However, since you asked for opinions, here is mine based on my experience.
The SP101 will be a bit of a handful with decent .357 loads and alternately using .38 specials in it for self defense would negate any advantages that a .357 would give you, so I personally rule that out. I have a Shield and carry it daily in a PJ Holsters IWB holster and for me it is the best compromise between firepower, concealability and controlability.
Before I get excoriated by the wheel gun guys for not choosing a revolver, let me state that
in my opinion, if a new shooter is starting from a clean slate, one of today's small slim autos makes the most sense as a carry piece. More available shots without reloading, generally lighter and easier to conceal due to autos having generally slimmer profiles. If you are a new shooter, the manual of arms for a auto is not really any harder to learn than for a revolver. There is no substitute for practice and before you start packing any gun around you need to shoot it a lot and become absolutely familiar with your piece.
Using the eight round magazine and loading one in the chamber, I have nine shots available for social work without a reload and it is so slim that I sometimes forget I have it on. The double stack grip of the Glock makes it just a bit harder to conceal under certain clothes.
There is no reason to limit yourself to just one handgun as I would rather have a longer barreled revolver or auto as a hunting backup. I personally use my 4" M29 as my hiking/hunting companion as I like the extra power of the .44 mag. But I have carried a 6" .357 before and it never got in the way nor did I feel under gunned.
As an aside, I love revolvers, in fact I have about twenty of them vs less than ten autos. However much I like them though, I feel that a small auto makes the ideal daily carry piece.
Here is a pic of my Shield in it's holster with an Iphone 4 for a size comparison.