Cloud Mangement for Amazon IaaS

I am planning to migrate few products on Cloud which will be used as a platform for the developer community. In short I am trying to host PaaS vendor for my products which can be consumed by developers for build and development process.

The plan is as below:

I am trying to use Amazon IaaS ( S3, EC2) as the hardware.
I will require a cloud management software which can be installed somewhere on one of my local systems and can manage the Amazon cloud.
I will deploy all my products on the Amazon Cloud with the help of the Cloud Management Software.
I will develop and provide APIs to my end users(developer community) to use my service as a PaaS.

What I am trying to achieve is as follows:

Vendor independence in terms of IaaS. Lets say tomorrow I move to another IaaS provider.
Customer support for the cloud management software.
Ease of setup and use for the cloud management software.

Evaluation so far:

I tried looking at Eucalyptus and it sounds promising, but I am still not able to find out if this will be supporting the public cloud setup as my requirement is. I believe this is more like a private cloud setup.
If anyone can help me compare the other available options, that would help me solving my issue. For e.g. RightScale, OpenStack, CloudStack, Nimbula etc.

There are several PaaS providers out there. There is a comparison here: Looking for PaaS providers recommendations

Disclaimer: I work for GigaSpaces, developing the Cloudify open-source PaaS stack. Cloudify answers most of your requirements, especially vendor independence - it supports a large number of IaaS providers, including: EC2, HP, Rackspace, Azure and others.

Cloudify does require its management server to run in the same cloud as the applications it runs so it can collect monitoring information using private communications rather then over the internet. Why do you want to run your management server on-premise?