is there a way to show/hide an entity as a whole instead of going through .show for each thing inside of the entity?
It’s been replied here:
https://groups.google.com/forum/#!searchin/cesium-dev/hide$20entity/cesium-dev/ol7edT6EtZw/NMO5FdN9c6EJ
Probably on v. 1.8 (fingers crossed :)).
You can uncross your fingers, I just opened pull request #2600 which adds this functionality. 
It also takes into account parent/child entities so you can do group visibility management.