Our 4 year old daughter has a loft bed, about 4 feet off the ground, with stair steps on one end, rather than a ladder (we felt much safer with a little one with steps than a ladder, especially with having to potty in the night, half asleep). We got it for her when she was just 3, it has a 6 drawer dresser that slides under the bed, and a desk that can be rolled in and out from under the bed, (with those two things removed, you could probably put another bed under there the perpendicular way if you wanted to) as well as 3 drawers under the stairs that lead to the bed. She LOVES it! We leave the desk out, since she has no used for it now, but later on, it will be in there - right now, that space, and the space left behind the dresser under the bed is a great "hide-out". I don't regret it, although she does have the smallest bedroom inthe house, so there is really NO re-arranging in her room, everything only fits ONE way. But once/if she gets tired of it, she will move to what is now the gurs bedroom, with accompaning bedroom suite, and little brother will get her set in his room. We paid about $1000 for the whole thing in cluding the new matttress.
It is like this one, but the dresser under the bed has 6 drawers, rather than shelves and drawers: http://www.monstermarketplace.com/living-room-collections... Ours is Dark Mohagany color.
We used to have a set of bunk beds, here for our niece and nephew when they were middle-school aged, that went together in the perpendicular arrangement, with a ladder, and a desk and drawers built into them, and we got rid of them, once we had our own kids. They would be ok for kids between 7-12 or so, but before or after that age, I don't know - questionable on kids fitting in them comfortably when bigger, and safety when younger - and again, with ceiling fans and lots of windows in all our bedrroms, there was only one place those beds could be in each bedroom.
Good Luck deciding!
Jessie