I think the first thing you need to decide on is your narrative style: first person or third person.
If you do the former, you could allow the reader a greater insight into a character's thoughts and emotions, especially the aforementioned character's reflection on his city. Another thing you could do with this narration style is go into the minds and hearts of the different characters you incorporate, writing in a different style (i.e. diction, slang, etc.) for each important character. For example, a lower class character might use a more informal, slang-filled speaking/narration style than an upper class counterpart, who might use a more formal way of speaking and have a more advanced form of vocabulary.
The third person narration style would probably be more apt for a lot of action going on at once, for example a battle, a large ball/dance, two characters trying to reach a destination before the other, etc. If you wanted the audience to get to know the characters and their part in the story more through their actions than their thoughts/emotions, the third person narration would be a good choice. The emphasis on action as opposed to inner processes gives things a more universal perspective, which provides an opportunity to see the character's actions as more interlinked.
It all depends on how you normally write fiction, and keep in mind that qualities of both narration styles can intermix. Also, you could try a combo of both styles, such as going a few chapters in first person, and then doing a chapter in third person as a kind of bringing-you-up-to-speed thing. Or whatever technique works for your story!
I also suggest that you think about your favorite authors, how they write, what aspects you like and how you might incorporate these styles into your own work.
And if you begin writing and find you're not really happy with the style, don't be afraid to go back and make a few changes. It's worth it.
Good luck on your story (be sure to post some on the forums; i'd like to read it!) and if you have any questions, feel free to ask.
