There are lots of childrens bunk beds available in a shapes and sizes. This is often a necessity if you have one room for two kids. Bedroom space will be maximize which makes it much easier to keep the rest of the house free from the spill over of toys. There are many childrens bunk beds that will help your kids bedroom minimize that problem of reduced space.
There are a few different designs that should be noted:
The classic duel twin and the twin over full size is the cheapest models available and will not help much in maintaining some degree of organization aside from promoting a bit more floor space for playing. This design is of course the the classic one bed on top of the other with a ladder on the side. This model is only recommended if you cannot afford a better design. If two kids are in a single room, it will be difficult to find adequate space for toy boxes, dressers and desks to keep the toys/activities at bay.
Nowadays, there are a several childrens bunk beds that have drawers built into them. Every nook and cranny of the bunk bed is filled with necessary drawers and spots to organize, be it toys or clothes. This model attached has drawers designed into the stairs to the upper bunk, in addition to under the lower bunk. There are many beautiful woods and colors that the beds are available in and are great for adding some storage to the room.
Desk attached bunk beds for kids are also available, and are useful for a lots of different activities like lego, drawing, coloring, homework and others. New generation children are quite computer savvy and a cheap computer can be great for reducing noise in the rest of the home. The shown bed has the attached desk and as a bunk bed with a full size bottom bunk.
Another style of bed is the hidden lower bunk with a computer desk built into it. If you have only one child using the room, but have frequent visits from cousins and/or friends for sleep overs, this is a great asset for adding more sleeping places. There are many drawers, cupboards and spots for storage which will maximize the bedroom floor space for play areas. It is 
fundamentally a full dresser and desk built into the bunk which similar to a captain’s bed. The lower bunk pulls out and is easy to tuck away when not in use. This makes it really easy for having kids for sleep overs. For a teenager and adolescents, this is a great design to give them their own functional space for alone time.
Bunk beds is a great way to add bedroom space and open up many available activities for your children or teenager. A bed the last example is a great kids bed and transforms well into an adolescents captain bed. Which ever childrens bunk bed you buy, ensure it is easy to dismantle and set up, but remains structurally sound. Children are well suited to find the Achilles Heel of everything they own and a well built bed will eliminate many headaches for the parents.
Good luck!