Fight Club for sure. Saw it again in a theater setup a few months ago and it's incredibly dynamic and powerful. The hallucination where the plane starts breaking apart had me thinking the room was going to explode, and the gunshot at the end is a thing of beauty..
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As Jay mentions, there are too many to name but one movie that I really like for it's dynamics over the course of the entire film that often gets over looked with all the SFX driven movies is "Forrest Gump". It really is an exceptional sounding movie that is mixed very well. It has really soft moments, to very punchy and loud (but clean) during the Vietnam war scenes. The score is wonderful and really pulls out the emotions during the movie, and scource music cues are great for tying in the historical eras of the story.
I also really like Contact, Fight Club, Heat, and The Phantom Menace. All "JarJar" jokes aside, it's one of the tightest mixes I've heard.
Mission Impossible - Ghost Protocol actually has a very inspirational and controlled mix. Obviously there are a lot of crashes, punches and explosions, but it is not over the top like the Transformers films for example. The music, dialogue and the effects are always very well positioned and in great balance.
Here is a clip I just found about the sound design of the film:
I found 127 Hours mix very exciting for all that it lacked. The more it lacked, the more exciting it actually was. It played to realism, and in such shots where we go from inside his headphones, to the exterior of nearly dead silence (what the real desert sound like) are incredibly dynamic.
Choose category “Sound” or “Sound Editing” and you will see the list of the movies with good sound. But don't use the checkbox “Winners only” since in this case you won't see “Avatar” and “WALL-E” in the list.
On a more subtle note I thought that Tin Tin had all around great editing and mix. The scene where the dog chases the cat around the room destroying furniture was terrific and detailed. Much less cluttered than many soundscapes, possibly due to it being an animation. I definitely concur with all the other titles. District 9 is a fave of mine.