they both started out on the bottom, and at ages 6 and 7, they usually sneak into the bottom bunk together every night, but they technically use both beds now. (we put a second mattress at the bottom of the frame- without a boxspring, there's room.) i like the bed because it has a small footprint, and the upper bunk is really short, such that i don't worry (anymore) about them jumping off of it- it's not very tall. (granted, they're 6 and 7...) in the long run, if you're aiming for your son to be up top, you could use the bottom space for storage/dressers, or a small table. it's not tall enough for a grownup to hang out underneath very comfortably, but it makes for a fantastic playspace -they're always hanging their comforters over the top bunk and playing "camping".
i have been following the convos here and wish to say more, but i've been out all day and i've got to get the kids to bed.
feel better, devaskyla! for reals, woman. feel better.