Love this play area over the bed, like the anti-loft bed. I think I'd leave off the first couple of steps of the ladder and make it a safer place for the older kids to play with and store their LEGO creations. (Apartment Therapy with loft bed inspiration)
Sleeping, working, storage and wardrobe space - you have space for it all with the STUVA loft bed. Sydney has something just like this in her room and underneath the actual bed is where she keeps her computer, lava lamps, etc.