I like mature trees and love walking among them (e.g., downtown Sacramento). In 99% of the US more trees would be better (and I try to contribute by planting an acorn or other tree seed when I spy a place a sapling might not get mowed, wherever I go). But I still consider more trees a distant second to buildings closer together, without room for trees (or, as typical, empty space or junk). If there's room for many mature trees, the place is fundamentally not dense enough to be totally amazing for a life of walking, as opposed to walking tourism.