*runs off to Google "Casa Bonita Denver"* Oh, my. http://blogs.westword.com/cafesociety/2009/01/casa_bonita_a_survivors_guide.php
Yeah, it might be wise to look up abandoned cities in America so you don't mistakingly think they're bustling metropolises anymore. Do that for any country you wish to put your story in, now that I think about it.
It's best when you're under 10 and don't have the capacity to notice how truly awefull the food is. Instead you wolf down your dinner and go off to chase the gorilla. It's a peculiar effect of growing up outside Denver, that as a child you see no other reason to go to Denver. The exchange goes thus: Parent: I think we need to go in to Denver tomorrow to pick up a washing machine. Child: ARE WE GOING TO CASA BONITA?!
I err on the side of inventing a city for the story to take place in. It offers greater flexibility to design the setting specifically to facilitate the plot.
There you go. Your characters grew up in a world far different from the one we have. So why waste time describing the world we have when it isn't even the setting of your book? I encourage you to write the places as your characters are perceiving them, that way, even though you know nothing about the cities, you have the ability to word the setting as you see it. The characters in your book know even less than you do now. They grew up without the knowledge of how our world works. If you put those handicaps into perspective, you'll see that you actually have a lot of leeway to describe the places however you see fit, even if it isn't grounded in reality. As far as the amount of research you do, I would keep a solid grasp of what major features each city has, that way you can throw references in that a modern reader could use to identify which city MC&C are in, even if MC&C don't have the slightest idea themselves. Think of Roland in the Dark Tower; We the reader knew where he was most of the time, even when he himself was oblivious.
Thank you so much, @Michael the Angel!! That's actually exactly what I needed. I planned on making some references to Disney when they get to Orlando (like rusted roller coasters and decaying signs), so I guess I can do the same for everything else too. It IS a completely different world. So I should write it as such. Thanks again.
It was my pleasure, and if you need someone to edit/review in the future, PM me and I will take a look.
