Hey Jim, such a tough question!!! I don't think I can answer with just one but here are a few that come to mind:

Black Crowes - Hard To Handle

I Aint Got You - Yardbirds

Spoonful - Cream

Close To You - SRV

Every Day I Have The Blues - BB King

All of these songs have killer blues rhythms, and leads -- plenty of licks and riffs to dive into here!

Mike