I agree with Absinth and your wife has very good taste. My personal favourites for a HQ are in no particular order:

Orchid
Saffron
Suburst
Azure
Sable
Aquamarine

Azure looks fantastic on a HQ van, Orchid looks amazing with white trim. Saffron looks really nice if accessorised right (wheels etc). Sable (and chrome yellow) look really nice with a splash of red (GTS grille and guard badges). Aquamarine is cool too.

It is all up to you! Here is a few to drool over courtesy of mr jones:

http://gallery.oldholden.com/Mr_Jone...rchid.JPG.html
http://gallery.oldholden.com/Mr_Jone...rine1.jpg.html
http://gallery.oldholden.com/Mr_Jone...urst1.jpg.html
http://gallery.oldholden.com/Mr_Jone...+Blue.jpg.html
http://gallery.oldholden.com/Mr_Jone...ffron.jpg.html
http://gallery.oldholden.com/Mr_Jone...able1.jpg.html