I went down on a couple girls when I was in high school in the movie theatre, so those are good places if the movie is not packed with people. Most had like 10pm curfews then, and little to no privacy at their places (although that never stopped me!
Once went down on a girl while her mom was washing dishes in the next room. She was freaking out, but didn't make me stop!) so we had to improvise locations to make out. Pick a back row, not the front or an isle seat, and wait for everyone to get settled into the movie! I'd talk them into wearing skirts and no panties to the movies with the promise of giving them something they'd enjoy while they watched the movie.
Just make sure to give them some candy to gnaw on, and a sweater to muffle their mouth if they are prone to being noisy. The floors are sticky in theatres, and it's not all cause of soda!