You could use green for your wall color. I like the tonal stripe of this room with the bright blue accents:



You could also do a bi-color treatment with the addition of moulding:

Why not add a bold gingham design wallpaper

Yes the green in the quilt is perfect, you can then get some declas that are removed easily as the baby grows like a chart for example or these
http://www.surfaceinspired.com/collections/monkeys-and-animals

A pale blue or even an off white with blue undertones. Check with your Benjamin Moore paint store or Sherwin Williams and ask them to help you find an off white with blue undertones. That way you won't be overwhelmed by blue ;-) Add in a few green accents that are near to the color in your crib linens and it should look quite nice.