When it comes to castle building and city building I don't want to feel like I am forced to jampack everything in. In games like Warcraft 2 you could build your villages spread out as long as you had the power to maintain the control of the area. Games like Stronghold Kingdoms and... gah, I forget... Has an outer wall that you can't expand outside of it forcing you to place things adjacent to others to get specific bonuses which resulted in a crammed ugly looking city.
I want to be able to build in style, without being forced to lose out on other things. I used to like building cities in Sim City as you could place anything any where and work around the pros and cons of placement rather than being forced to place in specific areas. Granted as you filled up your city you had to have a more dense building area, but that shouldn't come until end game and you should still have pathways/roads for units to move around.