[rrford]

Uhm, I am not quite persuaded that the "image" refers to the angels.

Here is the condensed version as I do not have time to dig out the full version.

I believe the first form of man that God saw was the person of Jesus Christ who was "the firstborn of all creation" and "the express image of God's invisible person."

That being said, God created Adam to look like what Christ would one day look like. Therfore, "Let us make man in our image" is saying "Let us form man in the image that the physical body of Christ will one day have."