Guanciale (is it banned in the US??? Why???) is cured pig cheek, and I find that I have come to prefer it to pancetta (cured pork belly) which is what I used to use.When re-reading your post, SS, I noticed the mention of guanciale, and since I didn't know what that is I later ran a quick Google search and discovered that a) it consists of items (especially pork) I don't normally eat and b) it is actually banned in the US, or has been.... Well, so much for that! In any event I prefer enjoying a bowl of Pasta Pomodoro the way it was meant to be appreciated all on its own.
These days, I use guanciale for the recipes that call specifically for it (Pasta Carbonara, and Pasta All'Amatriciana are the two main recipes that come to mind where guanciale is recommended, Italians insisting on its use), and, elsewhere, nowadays, I usually substitute it for recipes where I used to use pancetta, as I find it softer, moister, and more flavoursome.
It is delicious tossed through scrambled eggs, for example.