BFRPG Setting: Three Moon Forest

The setting I'm going to use for the boys' BFRPG game is Three Moon Forest, a setting originally developed for a 4E game that never came off. As its name suggests, Three Moon Forest is a massive woodland region. It may not literally take three moons' worth of time to cross from one end to another, but it sure feels like it. At the current moment, I have the following elements in mind for the setting:

1. Seven Forges - A dwarven settlement at the foot of the Kalderstones, a mountain range rising up out of the forest. The dwarves of Seven Forges ship their ore south, but lack easy access to river transport. So they move the ore overland to . . .

2. Last Landing - A human-dominated settlement at the highest navigable point on the Rusty River, a river flowing down out of the Kalderstones. Halfling-crewed barges take the dwarves' ore down river to other settlements while returning goods from the outside world up river.

3. Naddersfork - The next human settlement down river, located at the point where the Snake River flows into the Rusty. A stopping-over point for the barge crews.

4. The Hobshaws - The Rusty flows past this forested upland en route to Naddersfork. Since the Hobshaws are inhabited by numerous goblin tribes, that's a problem for trade. The goblins closest to the river have learned that toll-taking is a more profitable venture than outright raids, but there are always tribes further back in the hills looking for a piece of the action or trying to sneak a raid in when the river tribes aren't looking.

5. The Song Stones - Scattered across Three Moon Forest, these clearings contain ancient menhirs and serve as meeting sites for the elves of the wood—a more or less dispersed population with no fixed settlements of notable size.

What I'm missing is an adventure site. In the 4E version of the setting, there's an eladrin city that world-fell into the forest: its shattered remains are full of nasty fae creatures. Not sure how well that works as a mega-dungeon (or if I want to do the work of mapping it out). I'm not adverse to dropping in an established dungeon, but I would prefer one that isn't a meat-grinder for PCs: that's a portion of the Old School experience that I didn't care for as a teen and don't want to inflict on the boys. Thoughts?

(The image for this post is a shot of New Zealand's Pureora Forest.)