If you are hand piecing, I like doing Around the World... Everything is identical size squares (your choice as to size of square).
Just start in the center with one square, then add a square of a second fabric to each side of the center square. For the third fabric you start at the top of your second round and add squares all the way around making a diamond shape. Then just add rounds till it's as big as you want.
You can play around with the placement of your fabrics till you get the effect you want.
The one I'm working on now I started with the darkest square in the center, then shaded out to the lightest and back to darkest. Now I'm filling in the corners shading back out again to light.
The one I did before this one I just kept putting squares next to each other till I liked the way it looked. The pattern was much less discernable on that one, but it was very pleasing to the eye and my friend loves it!
What's really neat is that you can stitch continuously around because you are doing it by hand. And when you get to just doing the corners the number of squares in a round gets less and less as you go.