I've been looking for some time for a good graphical comparison of the New Jerusalem to the Earth. This site provides it:
And... it looks like you'll have to go there yourselves to see the pictures.
If you look at this one:
You'll note that if the NJ sat on the Earth, the edges of the NJ would be up in the air about as high as the narrow part of England is wide. Watch out for that first step, huh?
"If you are 1 mile away from the city, you would not see the top but might if you are 10 miles away. At 5,000 miles away, it would appear more than 130 times larger than the moon. To appear the size of the moon, you would have to be 160,427 miles away."
fair use for educational and discussion purposes at above link