I also puzzle a lot over fabric and pattern, and what has worked well for me...or at least has sometimes....is to make a sample block and see if I like what I get. Once I even cut 2 1/2 inch strips of 8 fabrics to see if I liked them together for a Trip around the World. I just laid them side by side until I liked what I saw.
I am never positive I will like a quilt until I am done. I just can not visualize the finished product, but these two ideas have helped.