Good news. I actually bought some tester pots of paint for my dining room and have samples on the wall. Progress is being made! I decided this was the perfect time to try out a new product I originally heard about from my friend Tina. A friend and neighbor of hers, Julie Boney, created a product called "Small Wall" which is exactly what it sounds like.
They are 12x12" adhesive-backed panels (that come 2 per package) that are ready for paint. They won't curl up like poster board, and you don't have to have color blocks on your wall. Genius, I say.

So, I decided to try them out for my dining room project . . . 
I wrote the name of the paint on the back of each sample so I wouldn't forget which was which. 
Champion Cobalt is the one on the right. It was the color from my original inspiration photo from Lonny.

Here's a closer shot. I really think it might be the one. I love it. It's deep and regal and saturated. Just what I was hoping for.
The other options I tried. Upper left is Georgian Bay by Sherwin Williams. Lower left is Blueberry by Benjamin Moore and the lower right is Farrow & Ball's Hague Blue color-matched for me by my local Sherwin Williams (because we don't have a Farrow & Ball store/distributor in Nashville)
There are other paints I could try too, but I don't want to get overwhelmed right now. Any thoughts or favorites? 

A special thanks to Julie Boney of Small Wall for giving me some samples to try. They really are a convenient and easy way to test out different colors. You can find Small Wall at most Sherwin Williams stores and some Ace Hardware stores. Just check Small Wall's website for a list of retailers. Also, thank you to the kind people at the new Sherwin Williams store near my house (on Hwy. 100 in Nashville) . . . they were extremely helpful!

Sources: Small Wall