Hi DR,
You can just change the colour weightings of the textures to look more lush. To do this, open the climate editor, then the land type editor for the grass land types, then go to the 'texture layers' tab, then click on the 'Col. Mod.' button, and increase the green value and decrease the red value (also, set enable to true). Something like 1.05 for green and 0.95 for red should do it.
As for the water map settings, I've not written a lot about it, but that which I have is over here:
http://www.bundysoft.com/docs/doku.php? ... orithms:wm
To make things lusher, you could decrease the 'max depth' setting in the water table wizard, increase the 'RiseParam' and/or decrease the 'FallParam'. I'm afraid trial and error is required to get what you want. This is dangerous though, as you may end up turning the whole map into one gigantic beach. Hence, I recommend adjusting the colour modifiers.
Cheers,
Aaron.