Rimbaud, I would think that you would need to set aside something like 12 hours to watch all the Extended Editions in one sitting.
I agree that the Extended Editions have replaced the theatrical releases as "the real films". Despite knowing that they would be superseded pretty quickly, I still couldn't help buying each of the theatrical releases on DVD when they came out.
Still, at least these Extended Editions do offer a lot more in return for the additional expense.