Do you have bunk beds or loft beds? I’m rather tired of them. I love my house, especially after we put on an addition. But it is a somewhat cookie-cutter suburban home. The bedrooms are very small. The smallest one is about 10′ x 10′. Place a window in there and it is awfully hard to fit furniture without blocking the window. (It made an adorable baby room, however.) With baby #2, we bought a new crib and put that in a new room. Then we added a bunk bed. When baby #4 arrived, we added a trundle bed so that 3 were in one room. 
Those bunk beds are now separated, but both girls have them pushed up against a wall. When my oldest son got big enough, we took him out of his sister’s room and changed the baby room into a boy’s room. We purchased a lofted bed so he could have a desk underneath. We eventually added a new bedroom for him when we built the addition, but it is still a fairly small room and with a keyboard and piano, his new bed is still up against the wall.
My younger son inherited the old baby room with the old loft. He got tired of the loft and I thought it might be fun to have the bed on the ground so that it could be more like a couch.  However, the bedding never stays tucked in. Someday I am going to have real beds with room on either side so that they look like the bedrooms in magazines! Also, since this was a lofted bed, the far side has a high, wood frame. You can’t just hang the comforter over that.
The two main challenges of bunk beds or beds against walls are
1. Making them – especially dealing with the bulk on the wall side.
2. Keeping them tucked in.
This is what my son’s bed looks like most of the time.
When the kids were first in their bunk beds, I made the bed covers and boxed the top sheet and the bedspread. By boxed, I mean that I sewed the corners together. I probably have a photo somewhere in my photo albums. But the basic idea is to mark a point on the comforter that is at the corner of the mattress. Bring together the green lines and stitch. It is similar to how we make boxed bottoms in our tote bags. The boxed cover lays over the corner of the mattress perfectly. I even did the same with the top sheet. This made it easier to make the bunk beds. Note – I made the comforter so that the drop on the sides was the same as the height of the mattress. This way, the comforter was tucked into the bed frame for a neat and clean look.
I was so tired of seeing my son’s bed undone every morning that I wanted to come up with a solution. I could have simply boxed the corners, but I would have also had to cut off some of the width of the comforter.  I am hoping to get his bed raised up onto a frame so I wanted to leave the comforter at the original size.
(Another note: my son is taking photography class this semester so he is taking my camera with him to school. I used my Ipod to take these photos, so I apologize for the positioning and quality.)
Position the comforter to drape almost to the floor.

With the comforter in position, mark the corners of the mattress on the comforter.

For the near side that will hang to the ground, tuck the comforter below the mattress to create a pocket. Here is the comforter tucked and lifted up.

Mark a stitching line from the top to the edge of your bed frame.

 Mark where the stitching should stop.

Stitch. This creates a simple pocket.

For the other corner, draw a line out to the side and bottom from the marked corner point.

Bring those lines together, right sides together, and stitch.

Here’s the far corner laying over my cutting table. You can see that the corner is now boxed.  As I mentioned earlier, you could cut the comforter shorter so that nothing is tucked under the mattress.

To add additional staying power, I added a piece of elastic to the far corner. I had a 2″ piece of elastic, so I stitched it about 8″ or so from each corner.

Here’s a look on the underside.

Here’s another look. To make the bed, start with the boxed corner on the far side. You have to tuck the elastic under the corner.

I’m happy to report that the base of the comforter has stayed put. Right now, the far side is also tucked in. I always think that might make the bedding too tight. I may eventually completely customize the comforter, but for now, I am happy with the foot of the bedding staying put.