This website I'm linking to is so good I hardly know where to start. The name nails it well - Every70sMovie. Every day writer-filmmaker Peter Hanson posts a review of a 1970s movie, a task he's been at since October 2010.
So yes, big. And an incredibly wide range of theatrical and TV movies are here. Random sample One:
The Devil's Widow (1970)
Only movie directed by actor Roddy McDowell, starring Ava Gardner and Ian McShane
Based on a Scottish myth, "The film begins at the sprawling Scottish estate of Michaela Cazaret (Gardner), a middle-aged woman of unclear national origin who populates her castle and its grounds with swinging young people."
(this is one of my favorite 70s movies by far)
The Last of Sheila
written by actor Anthony Perkins and Broadway composer Stephen Sondheim, but this is no musical. The story is that Perkins and Sondheim and friends were game lovers, played many scavenger hunts, and this murder mystery movie grew from that. It's got a fantastic cast - James Coburn, James Mason, Raquel Welch, Dyan Cannon, and more rich-and-idle characters who find out too late they are all soon to be victims of revenge
Hanson calls it a "jet-set caper movie.
Not even the tip of the iceberg of this site, which also lists movies by title and a giant list of names of all the players. Just go read and get lost for a while.