I've mixed Mama Bear Rosemary-Mint with Proraso green with good results. Since the Proraso doesn't have much of a smell it sort of dilutes the Rosemary-Mint a bit. Great lather though.
Williams by itself is a no go, but it is a monster when it comes to building lather. I use it sometimes with other creams like M. Real or Toms of maine. I get enough lather to do 20 passes if I want lol.
I experimented and found to like the ToBS Lavender Soap + GR Cream smells wonderful and gives a good lather. Not only does it pass my test, but also the gf scent and smoothness test (which can be much more stringent).