Ooh I like that! One quote I always imagined in the Silver Chair trailer is Puddleglum's speech about "a job like this, a journey up north just as winter's beginning, looking for a prince who probably isn't there , by way of a ruined city that no one has ever seen will be just the thing!" It might pair well with shots of them travelling, or the ruined city with flashes of Puddleglum speaking the lines in between shots.

"Love. Think. Speak. Be walking trees. Be talking beasts. Be divine waters. Narnia, Narnia, Narnia, awake..."

Yeah, they would totally rearrange Aslan's lines to fit a trailer or a poster.

"a job like this, a journey up north just as winter's beginning, looking for a prince who probably isn't there , by way of a ruined city that no one has ever seen will be just the thing!"

I love the idea of using that one for a trailer!

"Love. Think. Speak. Be walking trees. Be talking beasts. Be divine waters. Narnia, Narnia, Narnia, awake..."

That one in particular occurred to me to, and I have to say, rearranging it does work quite nicely. It would be great for a teaser combined with little glimpses of the humans staring in wonder, animals blinking, and the sun rising on a new Narnia. Maybe we hear Jadis' line "This is a terrible world. We must fly at once."

I'm thinking I would like the MN trailer to use some of the book's opening lines. They don't have to be in the actual movie, but this would be a great way to work them in.
“This is a story about something that happened long ago.... It is a very important story because it shows how all the comings and goings between our own world and the land of Narnia first began.”
Some other's from MN
"Have you ever heard of old Mrs. Lefay?"
“The moment I picked up that box I could tell by the pricking in my fingers that I held some great secret in my hands.”

I think a trailer should refer to the title, so using the lines “Ours, my boy, is a high and lonely destiny.” and “Men like me, who possess hidden wisdom, are freed from common rules” would be really great.

What about Reepicheep's song for VDT? If the focus of the movie is more on discovering wonders than "defeating the DARKNESS" then this might be a good voice-over for the whole trailer. Perhaps it would sound better spoken, not sung.