I found an article about choosing an appropriate needle size in the October, 2006 issue of American Patchwork and Quilting magazine. I tried to find the article on their website, but I think it's probably too old. It includes a very simple table on pg 82 titled "Task and Coordinating Machine-Needle Sizes."
I've reproduced the table below:
I've been using quilting needles for all of my piecing and quilting. I bought a multi-pack with sizes 75 and 90. I'm using the 75s most often, but I haven't been quilting or piecing anything too complex or thick.