I have also been making cities in my Minecraft world since 1.5 back in 2012. I find the terraforming to be the hardest part due to the tedium. What's the hardest part for you? Also, have you had to deal with update-born biome cliffs in your city? I like to work them into landscape.

Oh yeah, the terraforming part is very tedious, so I tend to just build on the landscape, as I feel the change in elevation adds a bit more character. As such, my areas tend to be quite small.

For the most part, not so much the biome cliffs though. I try to get rid of them any way I can– Biome Editor, MCEdit, adding more realistic transitions. Sometimes however it works out in my favor; a snow biome abuts the city of Delacroix, allowing me to put houses in a snowy Midwest-style environment, which is nice.

-MUP