Just wanted to share my experience at the "local" drive-in (I put local in quotes becuase I had to drive an hour to get there, but it is the closest open drive in to me)
We arrived 20 minutes before the box office opened, and there was already a line out to the street. The features this past Friday were "Finding Nemo" and "Holes" on one screen, and "Matrix Reloaded" and "The In-Laws" on another screen. Admission is $5 for adults and children 11 and under are free.
The lot for 'Nemo" was PACKED. There were maybe 5 empty spaces there by showtime. (I was glad we got there early and got a good space) "Matrix" was another story. I counted 20 cars on the lot by the time the feature had started.
The lot at the Mooney is gravel/dirt, and this theater has FM sound with a few speakers scattered around the lots. (Most poles were naked, and the ones with speakers didn't all work. I can't really fault them for not maintaining the speaker system that much, as there is FM sound) We happened to park next to a pole with a working speaker, so we clipped that to the window for the true "drive-in experience". :)
The snack bar offerings were reasonably priced, I had a Coke and popcorn which were both rather tasty. (Refills on large popcorns are free, but refills on large drinks are $1) The only "bad" thing was the restrooms, those could use a remodel.
Projection was decent -- for the first part of Nemo the optical soundtrack was projecting onto the edge of the screen, and there were some "interesting" reel splices, but I have seen things just as bad at the local multiplex.
I still had a good time, and will probably be back! (This theater is open year round) If you are in the Visalia area, the Mooney would definately be worth a look!