Number one in my book is multiple hight levels. I should be able to build roads underground, below bridges, above elevated stuff, etc... Number two is a more seamless transportation connection to neighboring regions. I want sims to be able to commute to neighboring cities without always pushing the boundary of moving out because of commute times. Number three is a more extensive railway system, i.e. highspeed trains, etc... Another, off topic comment. I think it would be cool if you could have a bus map overlay (Look at each bus route).