If I paint my kitchen cabinets a light gray........

Yes, I would paint your walls about 2-3 shades darker, for best results.

No go light otherwise it will end up too cave like. A bright white, a light blue, real pale yellow would all look good. Accents in navy would look awesome too.

When u have a small room darker colors make it seem even smaller paint the room light shades and then bring in the darker bolder colors by useing them as accent pieace's but just don't over do it another way to make a small space feel alot bigger is by useing MIRROR'S HERE THERE AND EVERY WHERE, DONT BE AFRAID TO MIX AND MATCH SIZE'S , SHAPES ETC... GIVE IT A SHOT LET ME KNOW HOW IT WORKS OUT FOR U

All so if u shop around you could find a place or some one selling a sky light and that would bring a ton of natural light in!

if you have very little natural light I probably wouldn't go with a dark color. It will make your kitchen seem even smaller. Perhaps you should try a couple of shades lighter than your cabinets. This will also make them pop in the room as well.

The dark a color is, the smaller a space will appear. Also a photo would help. What color are your counter tops, appliances and cabinets.

I would recommend painting the walls a lighter color as not to make the room appear smaller