There's a fascinating image in Genesis 18 today: Abraham's sitting in the door of his tent, three men appear, and immediately he runs to bow and greet them as 'My Lord'. Not Lords. They don't announce themselves, and he shows no doubt or hesitation about their importance or his duty to serve them. So I wonder: what must they have looked like? Did they approach like angels, bathed in light, eyes fiery, with the lustre of brass on their skin? I don't think they would've had fire-breathing horses or burning swords, given the occasion, but maybe their clothes and sandals were silver and gold?
I dunno; I just like to imagine how Abraham knew, right away, that this was the manifestation of God. I like the significance of the three-ness. For this occasion (literally the birth of a nation), just one of the three would not do - they didn't send Jesus, unobtrusive, or the Holy Spirit, mystical in dreams. No more God speaking invisibly to Abraham. For this news, they traveled together.
God is never alone. Imagine it.
Oh, and then while He's in the neighborhood, taking care of business, God goes to have a look into Sodom's behavior. You have to love a Lord who takes a personal interest.