Well I always feel that Slow motion has a powerful impact when showing a dramatic sequence. Maybe take a clip that has allot going on and slow it down. also as it is a trailer you need to jazz it a bit at the beginning. The slow moving text does not match the level of excitement that the clips themselves produce.

What editing software do you use?

This is a Video Game Trailer I made for a FriendJoJo(again probably not something your interested in) but it focuses on the the speed of certain clips. I hope my comments have been helpful. You have some great clips with good quality I think that with a little more editing work you will make a Great Trailer. Good luck on the project.