Also, I have no idea how denver is actually laid out (in real life or in Shadowrun), so when the players would ask me where 'downtown' was, I would point to a section of the map, and say 'it's right here!' and then that would be downtown. Luckily, nothing in the writing has contradicted me yet, but I keep waiting for it to happen.
The coolest thing is the the first few adventures really deal with each of the different zones, so crossing borders becomes a huge thing early on in the game, including coyotes and smuggler routes. My players found a smuggler dive on thier first or second mission, that they started using for planning.
-kv