Much agree to start with the Sarah cut.
You have a (lovely) round face - I do too - and the one time I got a short cut it looked bl*ody awful. It did absolutely nothing for me, it wasn't feminine on me, it emphasised my chin(s) 
and made me feel clumping and manly.
Ginnifer has got a gamine, Audrey Hepburn face, with a pointy chin, high defined cheekbones and quite elfin features. Sarah also has a thin-nish face but her cut is a lot more forgiving and suits a lot more face types.
Good on you for taking the plunge though! I have had the same long bob for years and years, although I do like trying out different non-permanent styles like bun rings and plaits. I have not the patience or the time to be blow-drying into a style and using wax etc for definition. Your hair also looks soft (not fine, there's lots of it, but soft) and this (like mine) does not also lend itself to a sharply defined cut like Ginnifer's.
Imagine how Ginnifers looks without the mousse and the thickening spray and the wax and the hairspray.. Sarah's will also require a bit of styling, but you can probably scrunch some stying spray in the roots for a more convinient day-to-day look.