I agree the Vaughn Williams Antarctica is a great orchestration. It has been imitated by many film composers. Of course it originally was a film score, for Scott of the Antarctic. He later made it into the 7th symphony. Vaughn Williams in general is responsible - along with Holst in The Planets - for most of modern film orchestration, along with Rachmaninoff in the piano concerti and Isle of the Dead (which you really ought to check out if you haven't already - incredible orchestration as well as themes) for the more espressivo styles. John Williams is probably most influenced by Vaughn Williams, Holst, Tchaikovsky, Rachmaninoff, Richard Strauss and Stravinsky (a couple passages from Star Wars are very similar to The Rite of Spring and the Lois Lane theme from Superman is a re-write of the main theme of Strauss' first tone poem.) That is not to say he is a plagiarist like James Horner, but rather he is so knowledgable that he is highly influenced by a lot of great music. But his own styule is unmistakeable, even if he is influenced by many composers which he is familiar with.
Anyway I am a big Vaughn Williams fan also. You ought to check out the Ninth Symphony, which has a more subtle but beautiful orchestration that includes three saxes and a flugelhorn, the 8th which has a second movement that is winds alone and third movement that is strings alone and a fourth movement with a huge compliment of percussion (including as Vaughn Williams said "all the 'phones and 'spiels known to the composer"), the 6th which has a quiet last movement that rivals Holst's Neptune for its eerie, metaphysical quality, and above all, the awesome Symphony in f minor, which is his most dissonant work and extremely powerful. That last movement uses a variation of B-A-C-H for the main theme, but transformed into a violent frenzy of dissonance.
Thinking about other composers who are influential on filmmusic is interesting - you ought to listen to Varese's Ameriques. It is a very powerful dissonant piece that is behind a lot of "suspense" or "horror" type film music. I agree with mverta about William Schumann being a very interesting composer. But also, from another era entirely, Robert Schumann with his intensely romantic symphonies has been extremely influential on film scoring. The egregious plagiarist I mentioned, the vastly overrated James Horner, stole directly his main theme for "Willow" from Schumann's 3rd symphony first movement. But that is another story...
You know a composer you might love? Sylvester Revueltas. A mexican composer who is not well known, but his Sensamaya, a violent and dissonant work in 7/8, is probably in the running for single greatest orchestration of the latter 20th century. Certainly one of the best. And as usual, highly influential among film composers.