Would you let your 12 y.o. daughter stay the night in a hotel with a 12 y.o. boy you don't know?

Okay so my grandma wants to take me, (15) my 12 year old cousin, and her 12 year old friend to a hotel for 2 nights just for fun. My 12 year old brother wanted to go, but my grandma is kinda...you know, strict about those things, and thinks its innapropriate for my 12 year old brother to stay the night there with the 12 year old girl. My parents think its unfair and won't let me go unless my brother can go too and my grandma is not budging, she doesn't think its okay. and i don't think its okay either. but i doubt my parents would have let me stay in a hotel when i was that age with a boy my same age that she didnt know. do you think its fair? and my mom keeps telling me if my cousin was a boy and brought a friend that was a boy that was my age, that i would think it was unfair, but thats not true either because i would understand that and i wouldnt want to chill with boys that age anyway, they are annoying. ALSO, my grandma is letting him stay all day to swim and go out to eat with us, and just taking him home before we go to bed, and letting him come back in the morning. all he is missing is sleeping. is this fair?