Bunk beds are a great solution for parents with many kids- they eliminate the need for more bedspace and cost less than buying separate beds, too. For parents who have many kids, and need all the space they can get, triple bunk beds may be a good solution as well. Three beds all stacked in the space of one will sleep three people, but can be rather dangerous with the added height. Safety is even more important with this added height than it is for double bunk beds, and should be the primary concern parents have when purchasing a bed. Make sure guard rails are strong and high enough to prevent kids from rolling out of the upper bunks!
Triple bunks stacked vertically also can present a problem with being too close to the ceiling. Make sure that the bed offers a reasonable amount of room before purchase, ideally at least enough room to sit up for the top bunker. One other way around this issue is to get a futon bunk bed in the category of twin over full bunk beds, or even full over full bunk beds. This will provide sleeping space for three or four without increasing the distance of the top bunk to the floor and can be a lot safer. They do require your kids' cooperation, as some kids may not want to sleep next to their siblings. The good thing about a futon bunk bed, depending on your preferences, is that many models can be converted to a sofa, providing kids with a place to sit when the bed is not being used. Do keep in mind that this can place extra stress on the frame and on the futon mattress, however, as more moving parts means more things can potentially go wrong.
In terms of bunk bed mattresses, getting futon mattresses can be the way to go regardless of the type of bunk bed you get. These mattresses are cheaper, easier to clean, and easier to move around and replace if the need should ever arise. They are also usually made with natural materials, most notably cotton. If you opt for this type of mattress, make sure the frame will support it. Futon mattresses tend to be thinner and the wrong kind of slats may be felt through the mattress.
Triple bunk beds can be a great sleeping solution for your kids, one that they will reflect on once they are grown up. Just make sure to do everything you can to ensure they sleep safe in their triple bunk!