Whats the coolest sounding movie?

Das Boot Director's Cut. It was released a few years ago. The sound is not showy with whiz-bang effects. The soundtrack absolutely puts the viewer inside that hot, stinky, leaky submarine. A must-hear Dolby Digital surround mix.

T2, still.

The Hit
with John Hurt and Terrance Stamp has very nice acoustical guitar and an excellent movie to boot.

Dead Man
with Johnny Depp has a beautiful soundtrack by Neil Young if you like a haunting electric guitar, this is also a very good (Jim Jarmusch) movie.

I just reread the original post and I am not addressing the question but I will leave these suggestions.

I second Das Boot :)

Saving Private Ryan and Fifth Element.

I agree The Haunting has some great sound effects. For a snippet of fun, check out the video sequence in the extra features section of The Lawnmower Man.