As you know, Ron Gilbert gave a postmortem about Maniac Mansion at GDC, and it, along with a bunch of postmortems for other classic games, has been archived online at the GDC Vault. Ron's talk is pretty much exactly the same as the one he gave in Germany prior to GDC, which has also been posted online, but at the very least the Q&A is different, so why not hear about Maniac Mansion's fascinating development again?
Those other postmortems are an embarrassment of riches, too.
Source: GDC Vault