I am looking to consolidate our current aws setup of 2 Large ubuntu ec2 servers and 2 large RDS server for our 3 websites that have a total of about 1.5 million hits a month and increasing every month with the majority of traffic (1 mil) to one forum site in the group and the rest of traffic to an ecommerce site and a small wordpress site.

So here is my question/thought?

Would it be better for us to combine the two ec2 large servers to just one and same with the 2 RDS servers so we run all three sites off one large ec2 and one RDS. -or- Should we setup maybe 2-3 smaller ec2 servers load balenced and a single RDS. -or- Something completely different setup?

One concern is that if one site crashes it takes with it the others. It happened in the past but I am pretty sure its because of the forum software and not the server setup.

-john