How clearly would I be able to see a galaxy with the naked eye if viewed from a "close" distance?
The surface brightness of an extended source in independent of distance. So for the surface brightness of a large spiral go look at M31 (The Great Galaxy in Andromeda) . What will change with distance is the apparent size, but the surface brightness will remain the same.

The surface brightness of a near edge-on galaxy will be greater than one face-on due to the greater number of stars close to any sight-line, and the integrated brightness will of course vary with distance.