My Little Narrative Problem

With NaNoWriMo coming up in a week, I thought I would start sharing some behind-the-scenes blog posts to go along with my writing.  This is honestly what's going to occupy most of the blog in the coming weeks, so I hope that I'm entertaining enough for you to keep reading over November (or as beardites will call it, MOvember).

I have a little problem about what kind of narrative to use for my novel (if you don't remember what my novel is going to be about, let me help you remember).  The problem is that I don't know who the narrator is.  Is it Larry, who is the main character for the book (in other words, 1st person narrative)?  Is it an observer closely following Larry's actions (3rd person limited)?  Or is the narrator simply Q (omnicscient 3rd person)?

The reason why I'm in this dilemma is because I am playing a few scenes around in my head (not writing, that would be cheating) and some of them - the opening chapter for instance - is perfect for 1st person, while others require a more sophisticated narrator than a high school kid.  If I go with 1st person, I feel that there will be places in the book where I want to use words and references that would be far outside of the main character's immediate grasp.

I exaggerate a bit - the character probably would know some of the things I'd write, but it's hard to make readers believe that when you're writing from a character's personal voice.  I also don't think I could accurately capture a high school student's mentality to within 90-100%, which means a separate voice would be helpful.  That of course ruins my "perfect" opening scene that I have in my head.

I know I can easily jump between narrative voices as I write, but I don't think that's very practical.  I should stick with one form from the beginning.

So does anyone have any suggestions?  I would love to write a scene both ways prior to November, but I then wouldn't be able to use those words for the story without rewriting them.  Any advice would be extremely helpful! :)