For the most part, I have used alcohol, denatured if I've got it, "rubbing" if not. It does not make flux magically vanish, but in conjunction with an old toothbrush, it ultimately gets the job done.
At one time, there was a spray on product called something like "Flux Off", which pretty much sprayed the flux away. It would also make Styrofoam and products like it vanish instantly, too! One could spray an entire coffee cup away in an instant! Because of that, and the expense, I changed back to alcohol and brush.
I, too, like to clean my pcbs. When solder had primarily resin in its core, I wasn't that diligent about it, but some of the newer flux formulations seem a lot more caustic to me.
