You can do a warm gray with a hint of beige that is on the lighter side. It will look more custom. Try Sherwin Williams Repose Gray. If this is too gray, try Worldly Gray. If you are looking for something beachy, but more on the fun side, you could try SW Rain or Watery

I would do navy with a white top and find some fun wallpaper or tile for the walls navy and white is very classic and I think would work well at the beach