It is easier to Wireframe, Mockup and create Final Site Graphics in Illustrator than in Photoshop . I still go to Photoshop for the more intense graphic treatments, and then bring those pieces into Illustrator. It is just easier to move elements around in Illustrator working on all your layouts at once.
The main reason I prefer Illustrator, would be the multiple artboards available in Illustrator. You can create the entire site, in one vast spread, and output mockups for your client in the various design stages of a Custom WordPress Theme .
You setup an artboard for each unique website template. It helps to name each artboard. Also be sure to keep everything in whole pixels. Don’t let any decimals creep into your shape positions.
Another Key Feature is the Symbol . You can create a logo or a header graphic, and then turn it into a symbol. You can then reuse this symbol on other artboards. When you edit that symbol in one place all the copies of that symbol are edited on the other artboards. You can then nest symbols within symbols.
Check out some of the results in our portfolio.