Below is a link to a site with excellent instruction, tabs, and sound sample to help one out of the "pentatonic rut" into which so many of us fall. It's been up several years, and was free for a long time. I think much of it is still free, but I noticed a small charge for one of the services (maybe a download of certain material).
Anyway, it's a great site, and much recommended. I have no affiliation with the author.
http://www.swingblues.com