After many attempts and serveral mistakes, here is what I am sticking with for my wall on my Nature nation.
Here are some of the constaints I went with in my build.
I wanted to use all 100 of the wall segments. This is alot, so I divided it into an outer wall perimeter and an inter castle protecting my storehouses.
I wanted to use the nature borders of my city map to stop ground units. As you can tell, I use the moat and the river to stop ground attackers.
I wanted to go as close the perimeter of my lands as possible. Nature is a ranged army, to have treants, longbowmen and Ballistas defending my walls would be a nice defense.
I wanted to space my gates to have sally points for counterattackes with mounted unit.
I wanted to defend as many buildings inside my walls as possible. I got at least 1 shrine defended, so no shrine rushing
So there will be a patch fixing some of the wall placement freebuild bugs in about an hour from now.
I had some early recommendations to anyone planning their territory defenses using free-build.
The first thing is to decide how you want to build. Concentrated or distributed.
If you want to concentrate in an area and tower it up, you are defending mostly against lower level players. Towers have less effect, in fact low effect against end-game raiders. However, this is good as there are alot of low level raiders.
Distributed works better against an end-gamer player. You make him have to spread out his troops and grab multiple caps before running out of time. Harass him with lots of troops to kill, he might miss buildings or spread out where his dps is lower.
If you distribute the only building to worry about are mana mines and storehouses. Keep those 8 builds as far apart from each other as possible. Stick a tower in shooting range of each of those buildings.
Everything else you can stick where ever. I like to make house subdivisions that mess with the raiders pathing, but that's optional.
If you have a mana mine point far away from the rest, you may want to think about ignoring it, and walling it up.
Ignore your gold mines/ore/lumber, these are secondary importance to a raider. Just make sure NONE can be capped at once. Nothing should be next to each other in range of a single troop cap.
You Keep is a 9th tower, but it's range is SHORT. Remember this.
The hills and mountains are pathing LOS. If you stick your storehouse on a mountain, you can stick other buildings around it to make it harder to cap from each direction. There will always be a way to cap it, but the raider my have to move his capping troops a couple times to find the right spot.