Below is my take on the situation from my experiences - lvl 32 party.
There are 3 different 'sets' of locations. These are labelled by a different geographical name which appear on the left side of the screen on the middle. These are Sandpoint, Lost Coast and Turtleback Ferry - from memory I thought I saw a Magimar set but can not see it now. Each set probably has an equal chance of appearing - though to me it feels like I see the Sandpoint set the most.
Each set has 8 locations. For parties with less than 6 characters the locations are chosen at random from this set. For 6 charecter parties you also get the same 8 locations (ie the full set).
On 6 Player Legendary the locations are also always in the same order. Which means there are only 3 different locations set ups possible.
The locations in each set are:
Sandpoint:
Village House, Wooden Bridge, Farmhouse, The Rusty Dragon, Apothecary, Prison, The Old Light, Junk Beach.
Lost Coast:
Thassilonian Dungeon, Shrine to Lamashtu, Throne Room, Warrens, Deeper Dungeon, Mountain Peak, Acadamey, Farmhouse
Turtleback Ferry:
General Store, Farmhouse, Wooden Bridge, Trechorous Cave, Acadamey, Waterfront, Village House, Woods
I would be interested to hear if anyone has seen anything different.