Matheson, interviewed in Twilight Zone Magazine about "Nightmare At 20,000 Feet", called Goldsmith's score "terrific". I wholly agree, but still I'd have to name Delerue's "The Doll" as my favorite score for a Matheson-written production.
In all seriousness, this is a GREAT score - Big, thematic, with a gorgeous end title from back in the day when horror films still had those. I can even forgive the blatant Stravinsky cops that pop up now and again...
How about Billy Goldberg's DUEL? That's always been a stinking, original and unusual work that fit its film perfectly.