Stephen,
Just to give an idea of what the 12mm end of the zoom will get you I now have two full frame shots at Hunstanton beach in my gallery. At the 12mm end the picture angle is quoted as 99 deg. Minimum focus distance 11.8" so you can get bags of dof.
In portrait mode you have to be carefull to not get your feet in the frame,
and in landscape mode you find people you think are at the side of you, walking unexpectedly into frame due to the wide angle.
In the Tides Out pic I cropped the left side to get rid of a bit of intruding mast and the bottom is cropped to loose my shadow, which can be another problem in a low sun situation.
Don