When developing an application in Java 7, would you say it's better to use the Pocket Guide rather than the standard API documentation or would you use both?
I can see how novice developers would probably require both but for those with more experience, which would you recommend?
The Java Pocket guide is just an aid that has reduced some of the basic and important information from the first two resources listed above.
My opinion is, frequent the Javadoc API... and know how it integrates with your IDE. And familiarize yourself with the JLS when you have time so you'll know when I how to reference it. And also, keep a version of the Java 7 Pocket Guide in your backpack, so you can flip through things when you are on a plane, in the park or in the lab.
The API documentation contains information about the APIs which a developer can use. So if there are new APIs added then one can find some documentation about it. But otherwise to understand the new features one would have to either pick a book which explains these features (like the Java 7 pocket guide) or make use of the official Java tutorials from Oracle.