Personally I would go with the SP101 .22 over the single six. Both are good choices, but when I plink with .22's I always like to do some rapid fire practice which the SP101 would be better suited for. Plus you can always cock the hammer back on the SP101 if you want to shoot it in single action.
Get good with a double action revolver, and you'll likely be able to shoot anything well.
I 100% agree with this. My first gun was a double action revolver, and if you can master a double action trigger, you can shoot just about anything.