I never knew this name is pronounced "VAWN". Every Vaughan I've ever met (which isn't many) pronounced it VAW-GAHN, just the way you see it. Have to admit that I really liked this name before seeing the way it's supposed to be pronounced, but I'm not so fond of it now. It's too monosyllabic for my tastes, and I don't like the fact that it rhymes with "Dawn", but I would never pronounce it VAW-GHAN anymore. Why? I'm not American, and I hate it when they spasticate our Irish pronunciations, so please people, out of respect for the Welsh, say it right.
This is high on the list of names I'm considering for my son. It is masculine, and sounds great on an old man, a little boy, and everywhere in between. It's a great name, and anyone who has it should wear it proud.