Resize Artboard: Fit to visible.
When dealing with a single page of artwork, resizing the artboard to artwork bounds does not take layers being hidden into consideration. So you have an artboard larger than your desired artwork.
Along with fit-to-artwork bounds and fit-to-selected artwork, can we have a third option for fit-to-visible layers, please?
Alex, I think that Fit to Artwork Bounds should just ignore hidden stuff...
On the other hand, if you need to fit your artboard to the visible art — well, you can just select it first and call Fit to Selected Art instead — so it is possible to achieve what you want... And you can automate it with an action that select all, fits, and then deselects. Sound like a solution, no?
There is another related problem to this one: An option to ignore strokes when using Fit to Artwork Bounds or Fit to Selected Art commands (http://illustrator.uservoice.com/forums/333657/suggestions/46067539)