I love FJ's old blueprints. They set the standard and spawned a million imitations (most of which can be found on www.cygnus-x1.net
Were they 100% screen accurate? No, but they were close enough for a make-believe world and fired the imagination. A few of the ideas are odd, a few of the assumptions differ from those of Matt Jefferies and some parts of it don't fit the modern view of the Trekverse (most notably the location of engineering and lack of a warp core), but it was all approved by Gene Rodenberry at the time.
And they're where we learned that NCC stands for Naval Construction Contract!
Here's a neat 3D flyby someone made, which does a lot to show the sheer size and complexity of the Enterprise: