ng14, I have a Bianchi OWB that fits the 2.25" SP101 pretty well and I think Bianchi makes a good product overall. They probably have something you will like - best would be going to a LGS that would let you try several out to see what you like. I have too many holsters stuffed in a drawer unused that I bought online or untried.
More options seem to exist for the 2.25" than the 3" so you should find something you like. Shoulder rig seems a bit much for a small revolver....
I have 2 'favorites' for my 2 1/2" SP101. First choice if I'm going to be carrying all day is my Crossbreed Supertuck. If I'm just going to be out for a couple hours or for around the house I use a Remora.
I currently carry a 3 inch sp101 and use a Sticky holster very similar to Remora and carried as a stock item by my lgs. I'd suggest for iwb carry if this is your first time carrying a revolver iwb buy one of these clipless holsters and experiment with carry position and depth. It will save you some money and space in your box of holsters. When I had the 2 inch sp I used a crossbreed and a don hume and neither were quite right for me.
At work I have to keep my weapon in my car. When I go to re-holster it at the end of the day that is one warm piece of metal to have against your skin.
Another reason is that I find it easier and quicker to draw if I use a OWB holster under an outer shirt. I can draw with only one hand just by bringing my hand under the shirt and knocking it out of the way at the same time I reach for my weapon. It's also more comfortable with my Forbus holster.
Then there's that non-extant hot weapon problem...