You could write a book....
Early on, they were family fun. I remember the 'Pic' commercials because the mosquitoes were terrible. The spiral green thing that you lit up and it smoked out the bugs.
[ame]https://www.youtube.com/watch?v=yUDISlDkGI0[/ame]
If the crowd got peed off about something they'd shine their lights on the screen and honk their horns.
As a later teenager, we went to drive ins but it wasn't for 'family fun'. In fact, some families probably got started at the drive in.

I remember well, the 'Planet of the Apes' marathon. We took coolers and had a regular tailgate party.
I snuck up on my now wife just to scare her a LITTLE bit. It got me three weeks of cold shoulder. Never did that again.
PT 109, Battle of the Bulge were two favorites when we were kids.
Flamingo, North 52, Gateway.... There were about a dozen in our town alone, and the 'town' wasn't much back then, but the drive ins did a thriving business. It was hard to find a spot to park if the movie was a good one.
Later came the 'Port' theater with x rated movies we watched from the railroad tracks. I remember 'He and She' for some reason.
We used to go to really crappy movies just for fun and giggles. We still laugh about some of those. Horror and Vampire movies were faves.
Here's some more memories..
[ame]https://www.youtube.com/watch?v=gr-0enrzvjs[/ame]