My comment about choke points was actually about how, in Native, choke points are more easily held by more defenders. Without the possibility of every flat surface being scaled defenders are much more common-sensical about where they position themselves. Additionally, as a happy byproduct, many maps are more streamlined because player tactics become somewhat more predictable.
One of my favourite non-Native siege maps is the wooden castle by the sea (the one that has some fires, a broken gate, and a huge facing wall). It's cooercive enough for attackers that ladder placement is very specific and, unless the need is dire, optional. I like it because it has lots of routes around the interior buildings and walls and lots of little aesthetic perks. What I find holds the map back, though, is that defenders can't leave the interior keep without significantly burdening the defenders on the wall. Because the facing wall must always be guarded against ladders, there are frankly too few players allowed into the main areas of the town to make it a good scrimming area. Though there are the occasional Rambos, the zone is, in effect, relegated to being scenery.