One of my all-time favourites is still just simple blocks of color. I'm working on one now that is just alternating beige and red 6" squares. It's as simple as they come. I tend to have several (ok, dozens) of projects going at once, and they are a variety, from super simple to more complex. My most complex at the moment is a lonestar with a drunkard's path border. The simple projects tend to get more attention. I find that I have a very low threshold for complexity in quilts. I quickly find them not to my liking if they have too much going on. I prefer simple, very geometric patterns.