This is about what I had in mind, updating as necessary of course. I'm more than appreciative of any suggestions.

I've used Redrobes's Thrubmorton Fens as an example:
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Thrubmorton Fens
Region 1, Map 7
By Redrobes
http://www.cartographersguild.com/showthread.php?t=1805

A large wetland makes up the majority of this area. The few ridges spanning the area make for natural trade routes, offering some protection from the more dangerous low lands.

Stockades and other fortified points have been placed along the trade routes to provide protection to those willing to pay for it. Most do, considering the dangers one faces when camping in the open.

The fortifications themselves are quite basic but well financed. Most maintain a stock of supplies available for purchase,

Agriculture
The region produces enough livestock and root vegetables to support the forts and the few outlying towns. Less simple foods like grains and fruits are imported, thus increasing the prices of items such as beer and wine.

Ecology
The low lands are full of swamps and marshes, and creatures associated with such an environment. Lizardfolk are common throughout the area and frequently attack passing merchants.

The higher lands are home to a wide variety of racial mixes, mostly due to the heavy traffic in and out of the area.

Adventure Opportunities
Mercenaries hired to ward off local predators
Ruins, caves, and disused mines long forgotten and buried in the wetlands
Battles between varieties of monstrous races affecting the civilized population