***There are spoilers in this post. Do not read further if you don't want RotG spoiled for you***
I know this thread has been done a couple of times (I did some research), but I'm going to make a more comprehensive post for an Eberron conversion of Revenge of the Giants. I welcome any and all suggestions and ideas... after all, that's why I'm making this post. 
Background and History of the Adventure (converted for Eberron)
---After the defeat of the rakshasa rajahs many, many (millions?) of years ago, the couatl and dragons established the Paragon Compact to safe guard to newely arising mortal races
---The giants were first the primary defenders of the Paragon Compact and helped construct the city of Argent in their empire to serve as a bastion against the forces of evil that had to be defeated. Many of the giants saw themselves as superior to the newly arrived "lesser" races and sought control of Argent.
---40,000 years ago (I think), the giants were attacked by the Quori Invasion. The giants used powerful and dangerous "dragon magic" to defeat this invasion, possibly even from Argent itself, to drive back this invasion in desperation to keep their empire.
---The dragons (agents of the distant coutals) were disgusted by this activity and helped wipe out the giant civilization, and gave control of Argent to the mortal races. All nations throughout history sent their best heroes (elves, goblins and orcs before the arrival of humans to Khorvaire).
---The Kingdom of Galifar and Dragonmarked houses become the biggest supporters of the Paragon Compact and Argent. As the Kingdom of Galifar rises to supreme power in Khorvaire, Argent begins to lose its support. It is soon almost forgotten about.
---Last War breaks out and Argent completely ignored while the nations fight for control. The last few defenders of Argent leave to help control or stop the Last War.
---They obviously never return and Obanar, the Last Guardian, awaits new defenders against this new threat. Enter our heroes, the player characters.
Sections and Enemies/Allies in the Adventure (converted for Eberron as best I can now)
Centering the adventure in Xen'drik
Piranoth - Rakshasa Rajah of Destruction
Torrians - ? Don't really like them. Maybe agents of the coutals and/or dragons?
Items of Argent - ? Don't like 'em either. My PC's won't want to give up their own items for these. Maybe make the items some that the PCs will want.
Divine Engine - ? Used by coutal to bind rajahs. Obviously using large, powerful dragonshards
Drow - Converting them all to Lords of Dust agents (they won't be drow, but humans/tieflings)
Acererak - ? Might just keep as is. My PCs will know who Acererak is and will enjoy this.
Astral Giants - Giants that didn't believe in the "superiority" of the giants over lesser races. Fled to Argonnesen with the dragons to learn from them more.
Court of Fallen Leaves - Eladrin Enclave in Xen'drik
Brown Anvil/Treeline - ? No idea yet.
Skewered Rat - Going to be a Xen'drik drow clan instead of gobo's
Forst Spire Island - Frozen island on south end of Xen'drik
Flamefall Tower - Volcanic fortress in mountainous region of Xen'drik
Releasing Piranoth - ? Don't like the idea of it being in the Elemental Chaos
So any ideas from anyone so far?
Rather than "elemental chaos", it's in the depths of Khyber. The various elemenal "rivers" are in fact chaos that's being created by the magics used to release the primordal.
Revenge of the Giants – Eberron History
As the Dawn War (the battle between fiends and the couatls and their dragon allies) came to a close, some of the remaining couatls established contingencies so that the newly forming humanoid races could defend themselves should threats once again appear. One of these contingencies was the creation of the city of Argent and the establishment of the Paragon Compact. This agreement between all of the civilized races of Eberron put in place a mutual defensive pact, with Argent as the first line of defense.
The Giant civilization in Xen’drik was the first rulers of the city of Argent, and their masterful creations and magical capabilities learned from the dragons formed the city itself. Over 40 centuries ago now, the Giant civilization in Xen’drik was invaded by powerful, alien creatures from the plane of dreams, known as the Quori. The giants used every resource they had, including the city of Argent to battle the Quori forces. The giants, losing the battle against the invaders from the Plane of Dreams, sought to use powerful dragon-magic to close off the portal to the plane and end the reinforcements of their Quori invaders. Not fully understanding the magic they were wielding, the giants caused massive devastation to the lands of Xen’drik, but were successful in ending the Quori Invasion. The giants were not fully successful, though, as their civilization was in ruins after the war. Once again, the giants went to use dragon-magic to rebuild their lands.
Fearing another devastating aftershock from the misguided use of their magic, the dragons attacked the giants before they could cause any more harm. The dragons’ attacks were ruthless and efficient, and the giant civilization of Xen’drik fell completely. The once proud lords of Xen’drik fell into barbarism and ferocity, their once proud nation completely in ruins.
The few remaining couatls and dragons rebuilt Argent and gave over the rule to the fledgling races of humanoids. The city was now filled with goblinoids from Dhakaan, elves from Aerenal, dragonborn from Argonnessen and humanoids from Sarlona. The purpose and nobility of Argent restored, the dragons fled into hiding into their mysterious continent to contemplate the Prophecy, leaving Argent to the mortal races.
As the ages of Eberron passed, so too did the rulers and Silver Cloaks of Argent. As nations came and went, the humans of the Nation of Galifar established the predominant rule in Argent. Each nation sent their heroes to serve for a brief time in defending the entire world from the greatest threats imaginable, and Argent knew peace and prosperity. Even as the Dragonmark houses were established, they too would send representatives to serve as Silver Cloaks in Argent’s defense.
As the lands of Khorvaire flourished under the rule of the Nations of Galifar and the mercantilism of the Dragonmark Houses, Argent was nearly forgotten. In a time of peace and prosperity, the defense against creatures of myth and legend were no longer needed. Fewer and fewer representatives came to the city of Argent to serve as Silver Cloaks.
And then the Last War began. As the nations of Galifar fractured and broke apart, fighting a never ending war, Argent was completely forgotten. Almost a full century has gone by now, with no one returning to Argent to serve as Silver Cloaks.
And now, as Argent sits alone and deserted, abandoned by the lands of Khorvaire, a new threat has emerged. Obanar, the last defender of Argent, has sent a calling to the Heroes of Eberron. He feels that he may no longer be up to the challenge before him. He doesn’t believe he can win, but he knows that he can’t fail. For if Argent falls, Eberron soon follows.