How to setup scalable hosting architecture/service?

scalable hosting

[thewpfan]

I am new at this, and I am building a blog network using WordPress/Drupal with a shopping cart and classifieds. Potentially (and any other website) this website may receive high volume activity and I wanted to plan ahead. If somebody could please recommend a hosting architecture and services that are scalable, I would highly appreciate it. Initially, I was thinking these phases as the website gained more popularity:

Phase I
Media Temple cloud hosting

Phase II
Media Temple cloud hosting with media stored on Amazon cloud

Phase III
Media Temple dedicated server with media stored on Amazon cloud

Phase IV (?)
Media Temple load balancing replicated dedicated server with media stored on Amazon cloud

Do I have this all wrong? Recommendations?

Thank you and look forward to hearing from you.

[thewpfan]

I did some additional research and found that this might be a better solution. This includes utilizing WP super cache.

Phase I
Dedicated Server on Grid Layer with media on Amazon Cloud.

Phase II
Two dedicated servers one for mysql database and one for web server, and media on Amazon Cloud.

Phase III
Multiple dedicated web servers pointing to one dedicated mysql database server, and media on Amazon Cloud

Phase IV
Multiple dedicated web servers and multiple dedicated mysql database servers, and media on Amazon Cloud

Any comments? Also, besides waiting for your server to crash, when would you move from one phase to the next?