Looking good! I really like the second one. When converting population to city size I work on the principle of having on average about 10 people to a building (in medieval times it was probably more but the data I've come across says that it is unreliable, I'm working on the principle that people living in the middle of the cities live in blocks), so a population of 20,000 people = about 2,000 buildings. From the sources I've read city populations in Medieval European cities have a density of about 100 - 300 people an acre. 1 Acre = 0.0040469 Square Kilometre. So, working on these (wildly assumptive) figures the size of a city of 20,0000 people would be between 0.8 square km to 0.2 square km.

Working on 0.8 square km city size, I fire up RPG City creator (a very clever bit of free software - do a site search here and you will find it). I make a city of 2,000 buildings covering an area of 1 km. The resulting generated city gives me a vague idea of what I need as a reference.

:: edit :: Ninja'd by Moe!