Another suggestion: 3-blocks long walls. It will very simply allow walls to be any length except 2 and 5 blocks. Currently they can only be multiples of 4, and building a long wall only to find out that you're one block short from squeezing that last wall in is maddening.
More generally put, I'd like more flexible walls. I think 3-blocks short walls is the simplest method. Something context-dependant similar to roads would be ideal but more complicated to implement.
Edit: A way to heal people? I'm not sure they heal on their own and there's nothing on trello about healing stuff.