Watch the Changing Voicings online guitar lesson by Vicki Genfan from Acoustic Rhythm Survival Guide

I've only given you one example here of using some different voicings for the I-IV-V blues progression. You may already know others, or if not there are many resources you can draw from, especially a good jazz chord book. It's great to have 3 or 4 different voicings at your fingertips so that you can change up the feel of your accompaniment.