Engagement question, ladies help, gents what did you do?

i want to propose to my girlfriend, we have been together for 4 years now. short story, i am happy with her and she is happy with me. i thought about proposing at the movies and in the theater having the screen in big text saying will you marry me, but there are a bunch of teens and im afraid they will ruin it and do idiotic stuff. ladies help out, how would you liked to be proposed? gents how did you propose? also, she is out in california right now, and i will be picking her up in 2 months at the airport, should i propose to her their when she arrives?