Which option is the most cost effective and uses EC2 capacity most effectively?
Configure Autoscaling group and Launch Configuration with ELB to add up to 10 more on-demand m1.large instances when triggered by Cloudwatch. Shut off c3.2xlarge instances.
Configure ELB with two c3.2xlarge instances and use on-demand Autoscaling group for up to two additional c3.2xlarge instances. Shut off m1.large instances.
Route traffic to EC2 m1.large and c3.2xlarge instances directly using Route 53 latency based routing and health checks. Shut off ELB.
Use a separate ELB for each instance type and distribute load to ELBs with Route 53 weighted round robin.