After several frustrating weeks of trying this on my own, I turned to 99designs. Wow! In 3 days I had several excellent designs to choose from. The designers were very polite and good to work with, and I was amazed at how quickly they'd resubmit changes and/or new ideas.
I will definitely use 99designs again. It's not only very cost effective, it saves tons of time AND you get top notch quality products.