I wanted to make the kiddos a bit more comfortable, but really didn't want to spend the $$ on a twin memory foam topper for each bunk and then have to trim it to fit. I took some measurements and ended up getting a 3" queen topper and cutting it in thirds sideways. I have three kiddos and didn't need the fourth bunk to have the added memory foam. The kids sleep much better now!
The topper doesn't quite cover the length of the bunk, but it's enough for the heights of the two youngest and almost long enough for the teenager. They have all appreciated the addition.
My rugrats are 17, 12, and 10.