A word of caution when using Exchange for GMail ...
When you delete a message it will get Archived (to "All Mail") and not actually go to the trash as you'd expect. When setup as a standard GMail account in iOS you have the option to change this behavior in your device's Settings, but when you use Exchange you no longer have this option on your iPhone.
To make deleted messages go to Trash you have to make the change directly on Google's servers. To do that, use your iPhone's Safari to navigate to m.google.com/sync and change the setting -- this can only be done from the device itself, not from your computer.
I learned this the hard way, I found 6 months of trashed e-mails sitting in All Mail!