ELB, CloudFront, SQS, SES ... it’s nice to have those things at your disposal even though alternatives exist. Consolidated billing, fewer accounts to log into (admin overhead) etc.
For applications that don't need guaranteed uptime or SSDs, you can save a lot of money with EC2 spot instances. I can get an m1.large instance and 80GB of EBS storage for about $27/month; comparable specs would cost $80 from DigitalOcean.