When trying to decide to demolish first so I can build the expanded version of something it would be nice if I could see how much money I would get back for demolishing, without actually having to do it.
Second that.
Related: when demolishing something that was just built and hasn’t been used yet, maybe give full money back? Without a planning tool (a la Prison Architect) making mistakes is very easy, and it is also very punishing.
This would be nice. Or have some sort of depreciation in the price over time, in case you unpaused before realizing something was broken, or forgot to pause for something. It’d also more accurately reflect the real world. I could see limiting depreciation to the stations rather than conveyors and such if you’re making the realism argument, and you don’t want each individual section of conveyor to have to have a variable.
Maybe there could even be construction time?
Building the layout using a planning tool and once you click on the approve button, it is getting built, but takes time. This could add some challenge in retooling your factory, especially in regards to expanding/improving efficiency while minimizing impact on the current production?
Not about demolition, but the time manipulating.
I like to play on very fast forward. But every time a new model gets announced, the time resumes to normal speed. Or when I load the file I saved on highspeed is starts on normal. Maybe the save file could save the time setting too, as well as the actual screen position and zoom. Not a big inconvinience, but I always get surprised when load a file. Like, where the hell I was working last time? 
Yup, thats definitely something I want to get in there. I also like the idea of a full refund for ‘unused’ slots.