TCM showed Paper Moon recently. I hadn't seen it in maybe 20 years, and it held up wonderfully. Ryan O'Neal plays a charming con artist who sells bibles to recently widowed women, and brings Tatum O'Neal along for the ride to teach her the ropes. It was Tatum O'Neal's first film, and she steals the film as a ten-year-old moppet who is not as innocent as she first appears. Tatum won the Best Supporting Actress Oscar for her very first role, then went on to co-star in the very 70's sports classic, The Bad News Bears.
Director Peter Bogdanovich shot Paper Moon in black and white, which effectively evokes the 30's setting.
I also watched Targets on TCM. Targets isn't a 70's a film (it came out in 1968), but it certainly exerted a strong influence on some 70's films, most notably Taxi Driver. It tells the all-too-familiar story of the clean-cut, All-American kid who hoards weapons like Travis Bickle before he goes on a murderous rampage. Working with a tight Roger Corman budget, Bogdanovich delivers a lean, fast-paced thriller.
I feel that Daisy Miller, Bogdanovich's 1974 adaptation of the Henry James novella, was unfairly maligned by critics.
By the way, the best audio commentary I've ever heard is Bogdanovich's commentary for the Citizen Kane DVD.