Hi! Residential is best for streets that don't have much connective value and do have residences, and unclassified is best for streets that have minor connective value or don't have residences. I generally don't mess with residential vs unclassified in suburban areas like this, so for the mapping I did in Cache Valley yesterday I merely extended the unclassified classification so it doesn't end abruptly. To quote the Wiki "the principle of maintaining network connectivity should be maintained at each classification level".