The intellisense in Atmel Studio does not currently work as well as it does in Visual Studio.

Atmel are working on improving the intellisense and have already shown great commitment to helping this project succeed. 

I expect that the Visual Micro plugin can also be improved to help in this area which will be a focus of development in a few weeks time.

Examples of Issues - Intellisense and Source Code Editor

• If you look at the number of Serial ports available to intellisense when, for example, an Arduino Uno is selected then you will see too many ports. The Uno should only display the "Serial" port, not Serial1,Serial2 etc in the intellisense list
• Source code that is excluded due to a preprocessor condition does not display as disabled text 
• GoTo definition seems to run out of steam and will not drive into core avr includes.

Whilst these issues are not show stopper they will be confusing for new Arduino users so we hope to see the issues resolved as soon as possible

Excellent! Thanks I will add a note to the Atmel page