A mainstream hollywood movie comes up now and again that's got a really good score. On the other hand, I recently saw the sequel to Pirates of the Carribbean. The entire two and a half hours consisted of the same theme over and over again with a few different rhythmic variations, and by the end of it I wanted to scream.
The Alfred Hitchcock movie The Birds is the only major motion picture I know of with no score or background music whatsoever, and the lack of a music track is actually very effective; the eerie quiet is more dramatic than an elaborate score would have been, but I don't think that would have worked in too many other cases.
Two other Hitchcock flicks, (and two of my favourite films,) Psycho and North by Northwest, have excellent scores by Bernard Hermann.
Basil Poledouris has also done some cool stuff, with Free Willy and The Hunt for Red October.
I am a fan of Danny Elfman, although a lot of his stuff tends to sound the same after a while.
Anyhow, my main point was about The Birds, so I guess I'll stop rambling.