Summer camp, definitely. Because all girls dream of that one summer that changes everything, that one magical summer under the strings of lights by the lake. Plus, with boarding school, the characters all have to be really wealthy, and it brings a sort of snobby tone. At a summer camp, it's kind of like one of those places where you feel like anything can happen, you can be someone new, restart with new people.
Edit: Plus, people are saying that it will only take place in the summer if you have it at a summer camp, but you can have it so that they end up going home at the end and realizing they live in the same neighborhood. Like, for example, this one guy at my school went away to camp and came back totally unrecognizable. He had gotten tanned, ditched his glasses and the slouchy hat he used to like to wear, gotten a haircut, his hair was a shade darker. He was seriously, unbelievably different, you wouldnt recognize him if you had known him. So things like that can happen in real life, its not impossible. Your character could end up going back home only to realize she already knew the guy (or whatever other character). It could show how things kind of changed once they got back home from camp, they dont talk like they did, it seems like it was a dream or something. (Like when you talk to someone online, but you still cant bring yourself to say hi to them in the hallways at school. That kind of feeling.)
