Well, there's been a tonne of ink spilled about Bezos' spiders' web. Everyone concludes that it's just nuts.
Have a look at this map. Long range octocopters, perhaps? For the 10 mile radius that Bezos mentioned, and given that most of the centers are more or less in the middle of nowhere (downtown Boston is sort of expensive real estate), delivery coverage isn't much. I saw a comment in my journey which postulated that Amazon would send out semi-trailers loaded up with flying spiders, find a central point, jack-in-the-box the top of the trailer, and spew thousands of spiders. Snakes on a plane seems tranquil by comparison.