Overall I would say that the Sierra documentation was much, much cooler and in depth. But I do not fault the Lucas guys for this. I think there has been a trend starting in the late eighties to cut costs of manufacturing by reducing the amount of cool stuff that we the consumer get in the box. Since the Lucas games really took off near the end of Sierra’s run, most of their games were caught in this trend and had very light documentation (like the rest of the industry). Monkey Island 1 had a pretty comical code wheel that created really silly looking pirates that doubled as the copy protection, but the further time progressed, the more sparse the cool stuff got. Some of the Sierra docs are still really cool. The cool puzzle books that came with the Dr. Brain games, the large history book on the California Gold Rush, and the neat investigative reporter stuff that came with the Laura Bow games are some things that are very memerable off the top of my head.
-Jim