Visitors like paths. But is it just the amount of paths, or the amount of money put into the paths?
Do gold/brick/marble paths bring more visitors to your island than stone paths, block per block?
Oddly, Stone Paths appear to be better at attracting visitors. To test this I filled one island completely with either sort of path.
Stone Paths: 185 visitors
Marble Paths: 93 visitors:
Some other stuff in my park changed between the two screenshots, but the stone paths I added in the first screenshot actually added more than 100 visitors on their own, so it seems pretty clear Stone Paths have unholy visitor attracting power.