Bookcase Backs: What Color to Paint?

A few weeks ago, I posted about the bookcases I bought for my dining room.  I am heading to IKEA soon to pick up doors for the bottom sections of them.  I also need to get to Lowe's to buy hardware to match the hardware on the desk and some crown molding for the top.

I know I want to paint the backs of these shelves, but I am torn on what color to use.  My space has yellow, pink, coral, seaglass green, and teal.  Like so:

So I could go with any of these colors.  What do you think I should do?

Yellow?

Image via Lamps Plus blog

Pink?

Image via Centsational Girl

Coral? 

Image via Chinoiserie Chic

 Seaglass Green?

Image via Holly Mathis Interiors

Teal? 

Image via Laura Casey Interiors

I'd love to hear your vote!  Tell me, oh bloggie friends, what color would you paint?

See you swoon,