Ooooh, this is a tough one. 
I'm more of a fan of the Bronze Age (and well, the late Iron Age too, I guess) so many of the Iron Age civilizations tend to have had a great and long history during the Bronze Age as well. 
I love the ancient Egyptians, Babylonians, Assyrians, Carthaginians, India and Greece (though Iron Age India and Greece, especially the Maha Janapadas and the Classical and Hellenistic Ages are more interesting than the Harappans and Mycenaeans, respectively). I can read cuneiform Akkadian, and have some knowledge of hieroglyphs since I was seven - I'm such a nerd, lol.

The kind of plot that I'd like would be to RP the intrigues in a grand city states. There could perhaps be different factions that the players might want to join, like a merchant's guild, a temple, a noble house, etc., and vying for supremacy. Another cool idea would be to have the roleplay take place at the start of the Iron Age, after the Bronze Age collapse, and have the story be about the end of the heroic age (Iron Age cultures like the Greeks looked back upon the Bronze Age as the age of gods and heroes).