I've also been having a lot of fun painting papers for backgrounds for my journal; here are the results:
I've used watercolors on some, acrylic paints on others. Most of the watercolor pages are sprays, and some of those used either plastic wrap or paper towels on top for added texture. For some of the acrylics, I put paints on a tile, put my paper on top, and brayered it. For others I scraped the paint on with a credit card. And on one I used a comb for texture. I've done several things I've not done before, and it was a lot of fun. I think that the watercolor ones will be easier to use as backgrounds - not sure how easy it will be to add anything on top of the acrylic ones - but I like them all (at least all of the ones I photographed).
These are all techniques taught by Sue Bleiweiss in her Journaling Techniques class.