Sarah, here are my few cents.
JCrew dress fits you really nicely at the top, you have nice upper body. I think if you shortened it, it would look even sexier. Which is a good thing, right?
I really like the AT dress, but I am not feeling it with that particular cardigan. Keep the dress for sure!
Laura makes a great point about the buttons on the pink dress. I like how the dress fits you though. What if you change the buttons?
BR sheath is classic. You will wear it forever. Keeper!!! And the hat is too cute. You look adorable in it. If you like to wear hats, it's a definite keeper.
AT pencil skirt is another classic. If you don't have a black pencil skirt, then keep it because it is a must have. It fits your really well. The blouse is really pretty, but perhaps you should wear it with other, lighter colors like grey or beige. Together, the outfit looks too dark.
AT blue blouse is very pretty. And such a great color that you can wear it with so many other colors. The M+O jacket is really something. Can you wear it buttoned up like the model? Great find! I am going to see if they have my size next. The pants look nice, it's always good to have a pair of well fitting black pants.
The blue dress looks really nice, cap sleeves and all.
I think I told you to keep everything so I really wasn't much help, was I? If I was to return any of the items, it would probably be the purple/pink AT blouse and possibly the pink dress.