could easily knock multiple thousand bucks off of that by just reserving the ec2 servers you know you'll need, plus reserve the cloudfront bandwidth you know you'll need (for the amount of data served I believe you should be able to cut CF costs by at least half).

3 year heavy EC2 reservations pay for themselves in ~7 months, cloudfront reserved bandwidth is just a 12 month agreement so that costs nothing up front. You might want to experiment with some different instance types though, depending on your resource utilization. Personally I really like using the new c3.large instances for my web servers and anything else that needs more CPU than memory, proportionately. If the standard instances suit your needs better you still might want to move to the m3 class.

Aside from those two items it looks like you are sending out a considerable amount of stuff from EC2->internet (27 TB transfer out from US-East to internet). I'd recommend looking at whether you could set up a cloudfront distribution with your EC2 servers as its origin.