The renovation of Monster Plantation to Monster Mansion is one of the major miracles of dark ride history. Somehow at Six Flags park circa 2008 (not exactly the best of times for the chain) decided to put that much money and effort into a slow-moving, animatronic-heavy boat ride with original characters. This goes to show that if park management believes in something enough they can make it happen.
This was always a stronger attraction that Phantom Theatre. It is sad though that by the end, the park saw a better use of funds in replacing instead of refurbishment, but I think a lot of that had to do with the fact that so little upkeep had been those last few years that the cost was too great.