I'd like to see tutorials on workflow. Everyone only seems to focus on synthesis and beat/loop creation - which are important for sure and I'm glad people are making the tutorials. But I'd really like to see someone do an in-depth study of shortcuts, workflow obstacles and how to overcome them, etc. How to really navigate Reason fast and efficiently, everything from keyboard shortcuts, to undocumented tricks, to bugs/missing features and ways to work around them.
I'd like to see tutorials on using blocks mode in Reason. There may be some out there already, I haven't looked... but that's an entire approach I've never touched and don't really understand, though the intro video Props did on it for Reason 5 made it look pretty interesting.