What's the best co-working space where you can book a day-pass?

Try myHQ subscription. They are an aggregator of coworking soaces and you can buy a pack of 1 or 5 or 20 visits which will give you access to multiple different coworking spaces including most wework.

I am curious about this. Why are co working places useful? What exactly do they offer? What are the use cases for you?

From my point of view, they would be useful if I am just starting a startup, don't have an office and need a place to meet potential clients.. but nothing more than that.