A couple of reasons that are important to us: 1. The ability to scale easily. This is going to depend on your application's traffic pattern. Is it predictable?

A couple of reasons that are important to us: 1. The ability to scale easily. This is going to depend on your application's traffic pattern. Is it predictable? If not, how costly is a failure due to an unforeseen spike? For us, since we host other people's communities, it's very important that we be able to scale easily. I'm willing to pay a premium for this. 2. Amazon builds into their pricing the cost of handling the day to day routine failures and the bigger 'oh shit' failures. Again, I'd rather pay for this directly rather than having it as a liability by either (a) paying someone on my staff to worry about it, or (b) ignoring it all together turning it into a hidden liability. 3. The Amazon architecture allows us to do things that we can't do elsewhere easily. For example: easily moving IPs between instances with Elastic IPs. This makes doing certain types of upgrades much easier. We boot a new instance with new software, make sure it's working, then swap the IP over. Also, the combination of EBS and S3 are a lifesaver for doing backups. Again, we're managing other people's data so I'm happy to pay a premium to do hourly snapshots of my data and continuous backup rotation through S3, with occasional movement offsite using AWS Import/Export. These are just some examples. Amazon makes many things easier, and only a few things harder, and on the surface appears to cost 'more'. However, I believe when you factor in the true cost of running a site, including all of the time involved in handling failures, designing architectures that have been designed before, performing monkey maintenance (swapping drives, power supplies, whatever), you'll find that the Amazon stack is probably on par or cheaper from a total cost of ownership point of view.