a quad cabin has two twin sized beds floor level with two fold down beds on the walls over the beds.
depending on your sleeping schedules you may all be sleeping at the same time but most likely not - due to music and friends and other things happening on JamCruise, not solely because of the quad set-up. My first year was in a quad and seldom were even 3 of us in the room at the same time - but we did not party in the room at all (there is a whole ship for the party!!)
That said, the cost of a double is only a couple of hundred more per person and well worth the privacy and room IF it is affordable for your group.
my experience has been with an interior quad - I have no idea of a quad/triple window or balcony setup