Stumbled upon a Korean graphic designer who makes gorgeous maps of world cities, including Tokyo. I have not used it yet (just ordered one), so do not know if it is the most practical – but definitely the best looking map I have seen.
The most striking part is that he has managed to combine a beautiful and functional layout with a nice design theme for each city. Tokyo theme is a circle based on the national flag of All Japan news (the round sun). For Osaka it is tentacle shapes (tako-yaki!) For Sapporo / Hokkaido it is a snowflake shape and for Seoul a yin-yang shape (Korean national flag). How he blends these design ideas in the map is truly amazing.
Check out his site: zero per zero design.
Maps can also ordered through White Rabbit Press.
Osaka area map (including Kobe, Kyoto, Nara)
Hokkaido area map