It is so dark in the kitchen!! Would you do a hanging light or add ceiling spot lights or something else?

both

Lighting as suggested; paint chairs yellow and place some art on the walls in the right-hand side of the screen.

Oh, a window treatment with bright colors would help.

Maybe think about painting the island a different color. A pale yellow might be nice for you. A fabric roman shade would allow you to bring some color in as well

Yes, it is very dark. I would change the island light to something more dramatic. Also adding under cabinet lighting would help, if hardwiring isn't an option there's on/push button options now. I suggest changing the stools to something with color. Accessories are key to bring in color, it's a perfect solution because when you get tired of something you can just change it out instead of having something more permanent. I would change the towels to something with a graphic pattern. I would add a big piece of art to cover up that phone jack and bring in a punch of color.

Some ideas to add a little brightness:

After removing the countertop clutter and trash can, add lighting. Recessed cans would help if in the budget. Perhaps add brightly colored pendants over the island, and under cabinet lighting. A piece of art on the empty wall next to the door. No to painting the pantry door yellow. Brighter counter stools. A few carefully chosen, colorful accent pieces on the counter. Consider painting the walls a cheerier color as the grey is a little drab. A new backsplash could also brighten up the kitchen.

Ii's all a matter of taste and budget. Your kitchen appears to be a good size with a functional layout. Good luck.

Granite and a subway backsplash, art, stools and roman shade.

Something like this (Solarius Granite), white subway tiles, maybe grey stools with a pattern top that includes yellow and carry that pattern into a roman shade over the window. The space has a lot of potential :)

Ok, so I'm going to get backsplash, but what kind? Should I stay away from the glass choppier kind? should I veer away from dark colored countertops? My cabinets aren't that "good" kind of wood, more like plywood. Can I still paint those? If so what color?

I am also going to add 3 can lights about the stove or sink. Get some art to go on the wall to cover the phone outlet to brighten the room as well!

Artwork on the walls that don't have cabinets.

As above comments already mentioned to paint island and add more light in kitchen ....About wall decor here's some suggestion for wall you might like.....for more Original ART check my shop too...

https://www.etsy.com/shop/PooArtGallery?ref=profile_shopname

If you like yellow, why not paint the walls a nice not-too-bright yellow? Uncover the window to let light in. Change the ceiling fixture to something with more wattage, add recessed lighting to brighten up the counters. Put in a backsplash or a washable wallpaper (easily changeable in the future). The island could be white or a deeper yellow.
Of course, with an open plan, you must consider the adjacent room or rooms and treat the area as a whole space.

Change the light and paint a lighter color.

If you are liking yellow, I'd suggest what felizlady said above, with painting an accent wall a light yellow with your gray walls. This will allow you to add a little pop in your kitchen without overwhelming yourself with all yellow. Also, maybe adding some color into your backsplash with white subway tiles.

Except replace the dark glass, shown above, with some color, shown below...

I like the idea of white subway tiles but my cabinets are "white white" they are kinda dull

There are multiple options of subways available to you with other colors. We have an option of doing a polished, crackled white subway, which is white with a cracked glass look or there are options of doing handmade subways that have colors as well.