If I would have to pick 2 wonders yet to be had in the series for each period these would be the ones:
Ancient era:
Gobekli Tepe: Screw the overhyped, overrated Stonehedge, Gobleki Tepe is
the oldest temple on Earth, an astounding discovery that have made us rethink everything that we knew about how civilization first formed: this type of temple might very well have been the reason why us humans started to build cities in the first place!
the Banau Rice terraces: An incredible complex and scenic feat of engineering, the Banau rice terraces brings into the table wonders from the less known region of Polynesia, and makes for a cool "food district"·
Medieval / renaissance era:
The laibela underground churches: So we need more African wonders? You bet! Do we need more uber cool underground wonders? Hell yes! This amazing constructions fits many, many blind spots in the game at the same time!
Nan Madol: It is always nice to have more sea related / enhanced wonders, and it is always nice to give more weight to the Pacific region. The fact that this mysterious constructions are shrouded in Atlantis-like mystery is just the icing to an amazing wonder-cake!
Industrial era:
the Transiberian express: The longer continuous railway might very well be considered a wonder, not to mention that it had a profound impact in the history and economy of the trans-caucasian region.
The Empire state building: Art deco and skycrappers need more love, me thinks. It is also quite perplexing to me how usuch an utterly iconic building have not made the civilization wonder rooster yet.
Modern era:
The Hadron collider: This is the biggest single machine that the human species have ever built, and one built with the express purpouse of understanding the origin of our universe. Nuff said.
Sillicon valley: Because the Internet is more of a technology than a wonder per se, and because Sillicon Valley has already proven to be a big influence of our times