Who wants to play paper doll?

I have a professional event/evening ceremony to attend in early December in southern California (so, mild/Mediterranean climate).

The dress code is cocktail attire/semi-formal.

This is quite out of the ordinary for my lifestyle -- I will play around in my closet but most likely will need to acquire something new.

What should I wear?

I am very much in brainstorming mode so I'm interested in both fanciful descriptions of what I might wear, based on your knowledge of my natural-dyed-literati style, as well as links to specific items if you care to share.

I will probably look secondhand first, but I'm also open to buying retail and putting in a reasonable investment, especially for something with a high longevity factor and/or remixable.

Thanks for any inspiration!