Just some inspiration pics for you. As you arrange, think in terms of vignettes, and not overfilling the space. And use what you have already instead of going out to buy stuff just to fill space. But maybe that is just where I am in my life right now!

Any suggestions on a color i could paint them to make them stand out that would compliment green wall? Navy?

you could paint the inside and leave them white to match the casings. perhaps choose the items you wish to display; if objects are white pottery, paint the inside dark. dark items, light color paint. maybe work from the colors in your stained glass windows.

i'd be reluctant to paint the outside of the cabinet...its rather diminutive and might make it look shorter.

It might be pretty to paint the inside one of the colors in your stained glass windows...

Before you paint the inside walls of the shelves, add some temporary color. Use a bit of two sided tape to mount a pretty paper, wallpaper, or fabric. Then if you decide you don't like the color you don't need to repaint.

Here is a corner unit that matches the table and chairs.

The picture Carol sent you below me (3rd one down) is fantastic. Paint your cabinet and light on the inside and bring in colors of the room. Love the one in the 3rd picture. Have fun with it. Balance, 3's and 5's, less is more.