I love the sound of Sisterhood and the Travelling Pants
Musicals are also good. Mama Mia is a good one as the girls love singing.
Having read through, and comments/discussion around age appropriateness. My thoughts are definitely in the 'pearl clutching brigade' camp, if that has to be how it's described.
I am happy, with mine and DH's guidance, to start tentatively watching films that are 12 rated with DD, if we feel they are good for her to watch overall, are present to address anything that is too adult/explain/fast-forward. But there is no rush for these things.
But, there is no way I will place myself in the position of making those types of decisions for the other children, whether or not they watch more 'adult' based films themselves with their own families. There are, clearly, plenty of movies that will be fun that are PG, that they won't have watched, so there is no need to venture out of any comfort zones during the sleepover. I want it to be fun, relaxed, full of laughter, with no come-backs. I would also like to not have to sit with them for the entire evening, but to be able to pop in and out checking on them.
There is one film DD loved, can't remember the name, awful film, but DD loved it, about a gymnast who was training another gymnast, about overcoming fear, and the trainer had some issues with a disabled gymnast judge, and it was all very nice and lovely and about friendship and working hard, with a little bit of sweetheart but no actual romance. Australian I think. That kind of thing is what I think she is after too. Any of those suggestions fit with that?
I am going to go take a look at Netflix and some of those suggestions below, and some others in google, to get an idea.