I have to admit I'm always puzzled by the interest in Gondor. What makes Middle-earth most appealing to me is the sense of small towns and villages separated by tracts of dangerous wilds and strewn with the ruins and relics of ancient history.
Bustling cities and verdant farmlands and an organized military? Not so much.
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Because Gondor is relatively civilized it is a terrific location for adventures/campaigns that focus more on intrigues and plots. Plus, it would have its own share of smaller towns and villages that are not detailed on the standard maps of Middle-earth. Gondor also borders Mordor and it has its own wild coast in the form of the Cape of Andrast (possibly home to more of the Drúedain, kin of the Woses dwelling in the Druadan Forst). The White Mountains are as well largely unexplored by most games and have their own potential for adventure. The same can be said of the border region of Harondor where the Harad Road provides a doorway to the South. There is also the addition of new Sanctuaries and Patrons in Minas Tirith, Pelargir (traders, pirates and spies, oh my!), Dol Amroth, etc.
Plus, a detailed, expanded map of Gondor would look great on my wall!