All of this except Django, overkill for many small and mid sized projects. I use a lightweight Bottle/uwsgi api to get json into _underscore templates. Up and running in ten mins :)
Shameless plug: I'm currently looking for beta testers to use this provisioning tool, so if you're interested in trying it out for your stack, send me a note (email in profile).
Another commenter mentioned that EC2 was relatively expensive. Technically, that's true, but the sheer power of being able to automate everything in the infrastructure is pretty awesome.