I try to go to local revival screenings whenever I can. Seeing Raiders and Temple of Doom after so many years was totally worth it. As was seeing Singin' in the Rain with an audience.
I saw Monty Python and the Holy Grail earlier this year, and the sound crapped out right when the cheesy organ music is supposed to start at the end. People just started whistling it! That group experience sometimes redeems seeing a dodgy print that's been in circulation too long. ;)