It would depend on what level your druid is right now.
If he is low level I would suggest going for 2 gathering professions to accrue cash. The choice of specializing in Leather working doesn't come until somewhere in the 50's level range.
As far as Herb/Alch goes, There is a ton of cash to be made from those professions from the level 68+ crowd. Raiders need Elixirs and pots to help progress through the raid content.
Hope this helps.