We would be building a facebook application in django(Python), but still not sure of where to host it economically,and with a good provision to scale in case the app gets viral. Some details about the app: i) Would be HTML based like a website,using django as a framework. ii) 100K is the number of expected pageviews in a day,if the app is viral. iii) The users will not generate any media content,only some database data will be generated by them.

It would be great if someone with more experience can guide on following points:

A) Hosting on google app engine or Amazon EC2 or some other cloud like RackSpace :

Preferable points found in AppEngine were ease of deployment,cost effectiveness and easy scaling.

For EC2: Full hold of the virtual machine,Amazon NoSQL and RDMBS database services in case we decide to use them.

B) Does backend technology affect monthly cost ? eg. would CPU and memory usage difference of Django over , for example , PHP framework like CodeIgnitor really make remarkable difference in running costs. ( Here is the article that triggered this thought process : http://journal.dedasys.com/2010/01/12/rough-estimates-of-the-dollar-cost-of-scaling-web-platforms-part-i#comments)

C) Does something like Heroku , which provides additional services over Amazon EC2, prove to be better than raw cloud management ?

It is not that we are trying for premature scaling, we just want to have a good start so that we are ready to handle unpredicted growth and scale.