I've both found and been gifted a lot of tiles this summer. They are beautiful and are mostly samples so they come in small batches. I'm finding the easiest way to make a cohesive design with a lot of disparate materials is to embrace the patchwork look of things and build your theme with color.
I tried to use some mix-in glitter with the grout but got distracted with trying to make nonsanded grout work with these big joints--a bad decision to use that goop--so I didn't pay as much attention to getting the right amount of glitter in the mix as I should have. So the effect is, uh, subtle.* But I learned some stuff and I liked how it turned out and now I'm going to pop a banana plant in this puppy and move on to the next project!
*Virtually undetectable. If you use glitter in your grout, I say commit to it and use more than you think you need.