The houses had three floors. At the back of each, on ground, first and second floors respectively, were the dayroom, lower (junior) dorm, and upper (senior) dorm/cubies. On the first floor there was the house mistress's bedroom, and at the front of the house the wardrobe and airing rooms. On the second floor was the maid's room (which by then was really a spare room for any guests or family that the housemistress might occasionally invite), and at the front above the wardrobe room and airing rooms respectively were little dorm, which slept about 3 (possibly 4?) people, and the box room, which I think slept 1 or 2.
Before the cubies were installed (around 1968, I think), upper dorm was one long dorm like lower dorm, and accommodated 16-18 people. Therefore being in little dorm or the box room, with only a couple of other people, was a privilege reserved for the sixth form. When the cubies were complete, they were really better than little dorm and the box room, as you only had to share with one other person, so little dorm and the box room were allocated to fourth formers who had just moved upstairs from lower dorm.
If I remember correctly, lower dorm accommodated 18, cubies 16, and little dorm/box room about 4, so the total capacity was about 38 girls. I think 5's numbers in my time only went up to 37, although I believe Jude's sig says her number was 38 (this was just after I left).
As for "acres of baths".....hahahahaha. There was one bathroom on each floor, each with four wash cubicles and three bath cubicles, covered only with ill-fitting curtains. The there were two toilets on each floor.
Generally speaking - though it depended on the strictness of the housemistress - we were not supposed to go upstairs during the day, not on weekdays at least. So we spent our time in house in the dayroom or, once in the sixth form, in our studies. The LVI study was at the very back of the house behind the dayroom, and the UVI study was at the front of the house just inside the front door. There might be around 10 in the sixth form, which meant that up to 27 first to fifth formers shared the one dayroom.
Other rooms on the ground floor were the house mistress's sitting room, the kitchen, the cloakroom and four loos.
It's scary that I can recall the layout in such minute detail 33 years later