In the Scalos prefs you can assign background patterns and choose which ones are used for the Workbench and the Windows.
That also reminds me that if you're using Scalos (which is what ClassicWB uses) then you don't need to use FullPalette because you can lock the palette in Scalos.
Another essential program I forgot to mention which is used for theming your Workbench is Birdie, which adds bitmaps to the window frames and can also remove the grey boxes from around icons without requiring another patch like NewIcons.
http://aminet.net/package/util/wb/birdie2000
You can see how the combination of VisualPrefs and Birdie looks on my 16-colour Workbench
http://www.amiga.org/gallery/images/..._CamiraOrg.png
I'm working on a few different themes, this is the SilverBlue one based loosely on an AmigaOS4 theme.