But if old-fashioned fluff or coils of steel leave you stiff and ragged in the morning, you can always pump up your nights with an air bed from a Sleep Number store. They sell six kinds. In fact, that's all they sell. One side of the bed can be very taut, the other side mushy. Your weight is one factor.
Personal preference is another.
The lower the number, the softer the bed. You can adjust it, play with it or keep it at a constant firmness level for years. By the air molding around you, it gives you more uniform support, especially back support. It's similar to a teeter-totter. That may depend on your budget.