In May, we had a quad cabin on Infinity. The sofa bed (where I slept) was only big enough for one. It was closest to the balcony door, which was nice for me--I was always the first one up and could sneak outside. The upper was on the wall above the regular beds. Hope this helps!
I think our cabin was 7195 or something like that...pretty close to the end, so the balcony was actually a little larger than our cabins that were the same category. Although it wasn't spacious at night, we managed with 2-19 yr olds, a large 15 yr old and myself, so you should be fine with smaller kids! Let me know if you have any other questions!