Nothing wrong with a simple design to quilt a quilt. My old quilts that my grandma hand quilted are very simple designs intended to hold the quilt together. They are beautiful and have survived heavy use for over 50 years. I hope that she enjoyed making them as much as I have enjoyed using them.
Flip side, I love to quilt my quilts. It's fun and it gives a purpose to my years of doodling on absolutely everything that I can get my hands on ;-) .
To pick a design I usually draw out my quilt pattern in EQ and then print out a few outline drawings of it. It gives me the main lines of the quilt so that I can decide what I want to do and where.