I'm not quite clear what you mean about the base64 option.  We can add unicode escaping for the JSON document.  It's still valid to escape unicode characters with `\u####` just like it is in regular JS, node.js just doesn't do that by default.

As for defaulting the region, I think most libs I've used have a default of `us-east`.

I tried getting the AccessKey and AccessSecret from env variables for other libraries. The issue is that I ended up choosing a different env var for each lib to avoid conflict and then I either added 4 different AWS env variables or reverted to inputting them manually.  I think it might be possible to do something there (maybe other libs have settled on standard naming).  Lets leave it out for this PR, and then we can handle it in a separate pull request afterwards.