Strumming techniques and playing with a good rhythmic feel are things that are so important for guitar players and often overlooked.

Honestly, I am having a little trouble with your question. Can you be a little more specific? When you say a riff using open A, do you mean an open A chord or just the open string?

Also, what exactly keeps happening? Are you searching simply for other rhythmic patterns to play to make it more bluesy? Could you perhaps send a link to a video that shows the playing style you are searching for?
:o