If you need a platform support for your mattress and could also use some storage you can hack two Ikea Expedit 5x1 shelving ... be handy if your bed will always be in a corner, I think it could ...

For example, you could get a daybed that has in-built storage for spare bedding or shelving for knick-knacks. You can also get a daybed with expandable options, such as a pull-out trundle bed ...