I sat my mono tape-recorder (one of those black, rectangular things with a speaker) along with my low-low quality tapes next to my clock-radio so that I could record the show. I would then listen to the tapes over and over. I lived in fear of someone walking in or by and talking.
Of course, I did not start at the beginning. No, I started with Episode 6. The show made no sense, but I liked it. Fortunately, they reran the show, and I got to hear it in its entirety, or almost its entirety. I think that I missed some episode in the 2nd season.
That lead to the books, of course, and all the hoo-ha that followed. Still, to me, the HGTTG is the radio show. Everything else is just an adaptation.
Strangely enough, I'm one of the few folks I know that liked the addition to the HGTTG films. Much of the radio stuff, which was all verbal comedy, did not translate well to a visual medium. I rather enjoyed the visuals and slapstick (most of it) that Doug added for the film.