I got a bunk bed for my 4 year old, and sh'es about to turn 5 and I've already gotten rid of it. Not that it was any sort of awful experience, but not the best either. Think about your little one when they first wake up. Do you really think it'l'l be a good idea for her to climb down those stairs while half asleep? Also, on occassion when my little girl needed to go potty in the middle of the night or when she first woke up, she wouldn't be able to get out of bed quickly enough and would pee on herself. It only happened once or twice, but she's been potty trained since she was two, so it was very upsetting to her. She really liked her bunk bed, but when I sold it she threw a fit for a day and has totally forgotten about it. Another thing to consider, is that most bedrooms have fairly low ceilings, and in our first house, it was summer and the fan was on and she went running up the stairs and hit her head on the fan. So we made the fan so you CAN'T turn it on, then we moved shortly after and the new house had the same problem in all the bedrooms (except the master), so we had to disarm this fan too. I like to be able to run the fan in the summers. If your concern is space, I think a great idea would be two twin beds with drawers underneath on opposite sides of the bedroom and they share a nightstand between them. That way you can put their bedtime books in the drawer of the nightstand, and you can use the drawers under the beds to store smaller toys or clothes, which will eliminate the need for some of the furniture you might otherwise need to fit in the room. Also, consider some shelving in the room so you can put some of their stuffed animals &/or toys on there, as they take up a lot of space, and that way maybe they can share a toy box between the two of them rather than each needing their own. Also, consider what the room has and doesn't. My daughters room doesn't have much wall space but has a big closet, so I moved her storage bins and panty/sock dresser into the closet which freed up some space in the room, and I started hanging more of her clothes than I used to, making some of the drawers in her room available for toys and other stuff.