1) A white shirt is never a bad idea, Perhaps you could play with the texture. Something with a subtle tonal stripe (but not shiny), something in a good herringbone fabric, those might all work.
2) If you don't want to go with a white shirt, maybe go with a very pale pink, and eschew the stripes, which could be a bit too businessy, and go for either a solid or a tonal pattern. (Yes, pale pink goes well with navy). Something like this Attolini (if you are a bigger guy) could look good: http://www.yoox.com/US/38532075/item?gender=U&cod10=38532075DK&kpid=US-38532075DK-10-PE16&adtype=pla&adpos=1o2&creative=81739559927&device=c&matchtype=&network=g&tp=107979&gclid=Cj0KEQjw0dy4BRCuuL_e5MeqmNABEiQAq8iNI_M5DGR3A_UdiVvISp0qMqnmST-gCtSvRv8VcvjS-FkaAtli8P8HAQ#cod10=38532075DK&sizeId=
The important thing is that the shirt be in a warmer, brighter, tone, that is both suitable for spring/summer (there are darker pinks that are more fall), and that lends something to your outfit, but is not going to jump out too much.
I would say that with colors like pink, that it really needs to be a high quality shirt, This is not a shirt to go budget with, or it will be just terrible, You don't need to google very long to see how pink goes terribly wrong.