I am looking for a framework to develop business applications. I see there is plenty out there and I would like to hear which one you would personally recommend:

Must-have Requirements:
Development (at least to start) should be graphical/GUI RAD approach involving objects (invoice, client, products) and processes (e.g. invoicing). Maybe drawing the process.
Possibility to enhance / change such generated code manually
Modern browser based front-end: Preferably in simple Apple-like look.
Front-end templates should be able to adapt to various screen sizes including mobile devices and different navigation specialities (e.g. no right-click available)
Scalability: Should be able to run on one of the big clouds like Amazon, Google,... and handle thousands of users in the future
License: Free or lowcost if possible at least in the beginning until we see that our business works

The framework should be around for a while and stable
There should be a market for freelancers / external companies out there that can be used to develop applications for us

Nice to have:
Possibility to contribute code improvements would be a plus
If possible there would be a repository for standard processes and standard objects
Market for 3rd party addons: free / paid

Your feedback is greatly appreciated!