In need: Formal Dress

My formal is coming up later this month and I need a dress...you know something spring time-y, something bright, something colorful, something fun! I found a few options online (two without sources...I'm sorry!!) but I am on the prowl! I ABSOLUTELY DETEST buying clothing online. I am the kind of girl who needs to try things on--it's all about the fit with me!

(Pictures clockwise: Shop LA: tiered mini dress, J. Crew: Vivette Dress, unknown, unknown)

What would you wear to a spring formal?