I think I'd prefer it if the blocks looked like actual blocks. Like solid snakes surrounding the tracks with a slight gap between each one. Then you don't need different colours. It can just be a translucent teal or something

Sometimes I'd like to be able to see the extent of my logistics network or my power coverage or the resting locations of my locomotives without having to go through my inventory and pick a relevant item to hold. Maybe pressing 'Alt' again could show all these things alongside chest contents, arm dir...