While I do like the idea of an air vent system for realism's sake, it would be so easy to get around it that it wouldn't be worth the effort to put in.
I like the idea of someplace more or less "safe" to do a bit of crafting, sorting or simply waiting out the night but I could do that nearly as safely and quite easily on the 3rd floor of the nearest ruin 6 nights per week. Anyone staying in their storage/crafting area on a 7th deserves visitors there. If you don't want to risk your safe spot on a 7th, and don't want to really fight the horde, go explore a skyscraper that night. By the time they do significant structural damage to it you'll have it mostly or completely looted and could care less if it comes down in a rain of rubble. The key to minimizing collapse risk in most structures is for you to not stay still very long, so the zombies keep moving too. That will hold in a17 as well as it does now.
I like the idea of someplace more or less "safe" to do a bit of crafting, sorting or simply waiting out the night but I could do that nearly as safely and quite easily on the 3rd floor of the nearest ruin 6 nights per week. Anyone staying in their storage/crafting area on a 7th deserves visitors there. If you don't want to risk your safe spot on a 7th, and don't want to really fight the horde, go explore a skyscraper that night. By the time they do significant structural damage to it you'll have it mostly or completely looted and could care less if it comes down in a rain of rubble. The key to minimizing collapse risk in most structures is for you to not stay still very long, so the zombies keep moving too. That will hold in a17 as well as it does now.