Same Time, Next Year (1978)

The cleverest structure on the list. George and Doris, each married to someone else, meet at a romantic inn and agree to come back on the same weekend every year, and the film drops in on that one room again and again as the years pass outside it. Alan Alda and Ellen Burstyn carry nearly the whole film between them, and the fun is spotting how each has changed since the last visit and watching them help each other through the crises in between. It began as a Bernard Slade stage play and still feels like one, which suits it. Choose this if you want the long-years effect in a warm, funny, intimate package rather than a three-hour spectacle, with the caveat that the premise is an affair and the film treats it gently.