Biosphere. God, what a metaphor! In other words, a self-contained inhabitable zone shielded from the harsh environment of--gasp--Seattle.
The whole point of locating in a city is to be part of the city. Let your employees meet for lunch at a local restaurant that hasn't been hand-picked by Amazon's Director of Restaurant Planning. Use the transportation system that the locals use, improving it for everyone in the process. Go to a public park to chill out, rather than a private park reserved for Amazon employees.
This kind of office park is all over Silicon Valley. To someone who's never worked in this environment, it sounds like a huge perk. But having worked in an environment like this, I'd rather just work in Seattle, not in a biosphere surrounded by Seattle.