LOL! Great choice. Layla was actually the first song that popped into my head. Specifically the version from his Unplugged album. He did an extended opening riff that I never tire of listening to and the performance has a bit more of a bluesy jazz slow laid back feel to it. I love how he tirelessly comes up with different versions dependent upon his mood at the moment. I can always find one to satisfy whatever mood I am in.
Okay Element. I was avoiding posting because this is really such a hard question for me to answer. However, I will share one of my many favorites because I can't stand the fact that no one has mention BB King here. Anything from him is a favorite but I love the multiple riffs throughout this song...