There are going to be single-host people and multi-host people. Their needs are very different. A bastion host might seem like overkill for a single host. If you can directly ssh into your db machine in a multi-host environment then I think you might be playing a little fast and loose. Allowing traffic to leave most hosts to the outside world is also something you should authorize on an as-needed basis, though with todays heavily-integrated applications this one is much harder (and often forgotten.)
Of course, since you are creating these AMIs and know the version of all the software on them, emailing me when I need to rebuild my machines on your latest images is a big value-add. Keeping up with security patches is a PITA. Let me also add in some common frameworks to include in your emails as a v2 feature (rails, php, java..)
Also, do remember that you're eligible for the PICPC-VC follow-on round! Ping me if you're interested. It's $50! Plus, I know your space pretty well.
Related to someone else's question, it would be great to also be able to use these images locally for development (e.g., via Vagrant, even if another step would be needed to import the images etc)
No particular recommendation, just one vote for Rackspace images here.