So, I found this guy's channel on You Tube, Vito Astone, who makes awesome backing tracks. He has this one in E minor that is in the style of a Steve Vai power ballad. After playing along with it a few times, I found myself playing things I've never done before, and phrasing in ways I've never phrased before. It's not saying much, but probably the best improv I personally have ever done. Warmoth Strat.
https://www.youtube.com/watch?v=uM57ppbxnMY
https://www.youtube.com/watch?v=uM57ppbxnMY