John Allspaw's books are great. I'd recommend these also:

The Art of Scalability http://www.amazon.com/Art-Scalability-Architecture-Organizat...

Scalable Internet Architectures http://www.amazon.com/Scalable-Internet-Architectures-Theo-S...

Enterprise Cloud Computing http://www.amazon.com/Enterprise-Cloud-Computing-Architectur...

Both of John Allspaw's books (the latter two on your list) look good from their table of contents.

And if you're in doubt, John is now VP of Ops at Etsy and came from Flickr before that: http://www.kitchensoap.com/about-me/

His blog is interesting too: http://www.kitchensoap.com/

So without having read the books, I would shoot for the latter 2 if I wanted to have hard copies around to introduce me to this kind of stuff.

I've found "Scalable Internet Architetures" by Theo Schlossnagle to also be quite valuable. It contains general advice on how to approach problem solving when it comes to building uh, scalable architectures.

http://www.amazon.com/Scalable-Internet-Architectures-Theo-S...

I'm a big fan of Building Scalable Web Sites - it's a bit old now (it predates cloud-computing-for-everything) but still very relevant if you're just starting to learn about this stuff. It's basically everything the author learned scaling Flickr from a tiny site to several hundred million photos.