In case you haven't been following all the collections at archive.org, here's an article that showcases some amazing science fiction episodes from the early 1950's Dimension X radio show. Fifty half hour shows are available at the archive.org site which should be a good TV replacement for a week or two.
From the site:
Dimension X made its mark by adapting short stories by acknowledged masters of the craft: Isaac Asimov, Ray Bradbury, Robert Heinlein, and even a non-genre-bound literary mind like Kurt Vonnegut. All of these world-creators knew well the value of imagination, and radio, in its way, stood then and remains today the most evocative, imagination-driven medium of them all.
(Score: 2, Informative) by Anonymous Coward on Thursday June 12 2014, @01:21AM
Wikipedia has a list of episodes [wikipedia.org], but no commentary to explain.
For these older shows, though, there were usually two reason for repeats: