Hello Everyone
This might sound very very stupid but you can explore anything behind instance portal inside instance by Turning Peerblock On and exiting instance, it'll just abort the transfer and you can explore anything behind it (like Suken Temple) but sadly, some portals have solid walls.
Things behind Stratholme (Main Entrance)
Old Thousand Needles behind Zul'Farrak
A lot more to explore! Hope you get the idea