The techniques Ewan outlines are spot-on; my clarification is for people to have the right expectations of the Micro's, not on the information he provides on tuning a WordPress install.
That said, Smalls and up on EC2 will give you more consistent performance (they aren't built to provide the spike-performance Micros are) BUT are still relatively subject to "noisy neighbors".
The smaller the instance, the bigger the impact felt; it is still possible to have a small grind to a halt because of a noisy neighbor and typically I do not see people hosting web front ends with smalls because of the erratic and poor performance (in general). Possibly a fleet of them behind an ELB, but even then I see Mediums and Larges much more often as the "web server".
The mediums provide an awesome (and typically unsung) balance between monthly cost and performance on your way to a large (which can get quite expensive).
Great makes a lot of sense thanks for expanding. Like you touch on I think price is the big issue for most people who aren't looking to build for 15mm/month but are just looking to sleep at night knowing that getting to the frontpage of digg, reddit, techcrunch, hackernews, etc won't sink the ship.
That said, Smalls and up on EC2 will give you more consistent performance (they aren't built to provide the spike-performance Micros are) BUT are still relatively subject to "noisy neighbors".
The smaller the instance, the bigger the impact felt; it is still possible to have a small grind to a halt because of a noisy neighbor and typically I do not see people hosting web front ends with smalls because of the erratic and poor performance (in general). Possibly a fleet of them behind an ELB, but even then I see Mediums and Larges much more often as the "web server".
The mediums provide an awesome (and typically unsung) balance between monthly cost and performance on your way to a large (which can get quite expensive).