Personally, I just design the menu so that the longer menu items do flow onto a second or even third line if required. You have to use padding instead of text-indent to provide the horizontal spacing in this case.
As for your original request which would resize the width so that the
menu items are always only one-liners, I think that's a good idea for
a separate plugin that you could then add to the function chain after
Superfish.
$('ul.nav').superfish().submenuResize();
Joel Birch.
