I like the idea of yellow since it is the colour in the smallest amount in the quilt. Have you thought about a flange binding using a narrow strip of yellow and then blue. Here is a link to a tutorial;
http://www.jaybirdquilts.com/2010/12...-tutorial.html
There is another method for flange binding using both colours and sewing them together first (one is slightly wider than the other) and then sewing on the binding. I know there is a tute for that too but I don't have the link.