I'm also considering adding white gouache in places for more interest. I don't know. There are parts that I think look a bit awkward (like the circle with the weird purple spiky things) and maybe the white gouache will tone them down.
I really like this new Aquabord that I tried. It's like a canvas board for watercolor paints. I bought mine at Hobby Lobby, but it seems there are a bunch of online dealers that sell it too. It doesn't absorb as quickly into the surface as paper, but I like it a lot because you don't have to worry about wrinkling paper and the board itself is actually not the expensive. Another thing I like is that if you want to remove a color or blend a color, you can get a napkin wet and wipe it off so it's lighter.
Here are some detail shots.