I only made diagrams for two situations, but you can apply these to any situation or part of the map:
River Defensive Line
This is what people usually build, for some reason:

This is what I think people should actually be building (or at least, something along these lines):

Crashed Shuttle Tunnel Forward Hive
This is the "forward hive" that people tend to build starting at the crashed shuttle and then extending towards the water plant/table fort area.
This is another defensive situation that people usually screw up by placing lots of single walls and obnoxious doors. Here is generally how I think it should be done:

Obviously these aren't perfect, and somewhere out there is a better hive design than these. I'm just trying to get people thinking about how to make better hives than the crappy one-wall-line ones I see all the time.
And yeah, some of these involve a lot of wall segments, but it's not a big deal if you're a hivelord or an upgraded drone. Especially if you have some other xenos helping you build who kind of understand what you're going for.
Thoughts/comments/suggestions?