It would be beneficial to group resources by actual service (i.e. EC2, etc.) and then group them one level deeper by what it is (i.e. Subnet Groups, Instances, etc.).

So if someone wants to know what they utilize from the EC2 service they can filter by EC2 and see all the things like Instances, Subnet Groups, Load Balancers, etc. instead of having to select all of these in the filter.

This would add a tree-like structure behind the scenes that could even be implemented in the GUI someday.