I am still in a state of disbelief about this whole one tile thing. It really only makes sense if moving improvements to a subscreen actually dramatically reduces memory usage and I can't bring myself to believe it. If it somehow does get implemented I hope they chuck the building placement screen idea. That seems like a whole bunch of work and memory usage for no reason what so ever. The only reason to have it is so that all the existing artwork doesn't get wasted and that's a horrible reason.
Except for the memory usage the current system works fine, there is no reason to change it. You could easily limit the more extreme cases of snaking by limiting how far from the city center you can build. As for the distance thing no measurement in Elemental makes any sense what so ever, literally none. Gildar, turn length, tile length, and whatever are all assigned rediculous values. Civ has the same problem bacause really the entire concept of playing a game that lasts several hundred or thousand years is a rediculous concept.
Sure cities might look slightly more impressive and realistic under a one tile system but only at the cost of all of your cities looking exactly the same. Which kinda seems like it will kill city specialization. How would building beside resources work under a one tile system? Are shards going to be the size of the the entire city? Are lumbermills being removed?
Sieges. Do it. Do it. Do it!
I'm not sure how moving to this system would make implementing sieges easier. Sieges have been pretty much declared a no go several times already.
Personally I think a hybrid system would work the best. Seperate improvements into major and minor ones, with only major ones creating visible improvements on the map. Then have houses randomly generate around the city like suggested. Bakeries and workshops for instance would be minor but castles and unique sctructures would be major. This would reduce memory usage but cities would still look unique. This way you also wouldn't need a weird sub screen for cities. Also building beside resources wouldn't look weird.