A few tricks you can do to make your blues a bit more jazzy when you are improvising is to imply a 2-5-1 lick in the 4th measure of your 12 bar blues. For example, if your in the key of A in the forth measure imply an Em7 and an A7alt in your lines and it will create nice tension as you traverse to to your 4 chord. Of course there are many ways you can imply the A7alt sound. An altered scale, whole tone, dominant diminished, b5 sub arp, are great devices for this sound. The combinations are vast thus making this technique a fun and seemingly endless supply of fresh lines to jazz up your blues. Robben Ford, Scott Henderson, John Scofield, Mike Stern, are some resources to hear this in context. I think these guys are good examples of jazzy/blues guys maybe leaning a little towards jazz.
Give it a try and let me know how you fare! Cheers!
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