I toured both Matilda and Adventist prior to confirming at Adventist. I just called up the maternity unit for each and arranged a convenient date and time. The Matilda seem to be available for tours during the week at lunchtime and Adventist just prefer you to call up a couple of hours or so before you intend to visit so they can check how busy they are and which rooms are free for viewing.
Both hospitals are very nice and I don't think there's much difference between the two.