I'd start with this jacket from J Crew Collection. I love it! It's a little out of my budget at the moment but maybe it will go on sale or magically appear in my size at the outlet. But this will last for many years. I also love it with jeans, but not for cocktails.
I'd put something fun underneath it like this sequin t-shirt also from J Crew. I have a solid black one from last year that has long sleeves. This one is more fun. This is also versatile.
For pants, I came up with two options. Both of these are from J Crew. I like these below, which are more festive. But not everyone can wear these. Second option is a more tailored black wool. I like slim fitting pants.
For shoes I came up with two options. I have a hard time wearing heels due to a foot injury. Belgian loafers are a must. These came from Barney's. You can buy versions of these in different brands. The real Belgian Loafers (order on-line from NY) are wonderful.
For jewelry I would go "light" on the earrings and more bold on the necklace with the pink jacket. All the jewelery below is from Monkees of the Village in Winston-Salem, NC. They have a good FB site.
I like the black necklaces on the bottom row:
You need a cute handbag. For that I would defer to Kate Spade. I am loving her bags right now.
Hope you like the outfit. I think dressing up at the holidays is so much fun! Have a great day!