Okay I just looked at a few ingame paths. The asphalt path has Esthetic Bonus bonus of 4, The yellow brick path is 10, redbrick is 6, dirt path is 2, concrete/white brick is 4, sand is 2, stone is 6.
Since the yellow brick path is considered the most special of the ingame ones, I would guess that all the ingame paths range for 2 to 10.