What to Wear?

A friend of mine and I are hosting an Engagement party in the end of March and I need something to wear. 
Clearly, I need an outfit ASAP to ensure everyone has a good time. 
Here are some options I am thinking about...
This draped denim number is by Maeve from Anthropologie.  Cute, right?  I am picturing it with a cool blazer and a skinny neon belt.  Naturally with some killer wedges...

This is a total pie in the sky dress...but oh so perfect.
It's T by Alexander Wang from Saks...and I need it.

I forgot to mention this is an early evening party complete with croquet and corn hole! 
I can't wait!