I've got a good bit of first-hand experience with this. The right answer depends a lot on the app and architecture. Do you have to maintain state/session over

I've got a good bit of first-hand experience with this. The right answer depends a lot on the app and architecture. Do you have to maintain state/session over a long period of time? Can requests be load-balanced across different web servers or do they need to stay with the originating server? How much content can be static? How long can the data be cached for? Will there be high-demand customers or topics/trends? (eg: think of how Twitter has dedicated Justin Bieber servers) Will the traffic be bursty or climb steadily? Is there a need for comments or user input to show up in real time? Does the content mostly come from users, or from some structured input on your end? Does the site architecture lend itself to elastic scaling (either from your own standby machines, or EC2 style servers)? These are just some things to think about.