Hi ronfla,
There is more about choosing a bedframe in post #10 here. The Simple Life foundation or the wood slat foundation would both need a suitable steel or wooden bedframe to raise it up off the floor. If you are buying a wooden bedframe instead of a steel bedframe then I would make sure that it has at least 5 hardwood cross slats with a center support beam with good center support to the floor so it would be suitable for supporting a foundation.
If you are buying a platform bed that has a support surface (similar to a foundation) with enough slats to support the mattress and the distance between the slats are less than about 5" apart (4" or less would be better) so that the mattress doesn’t sag into any gaps in between the slats and it also has a center support beam with good support to the floor then it would be suitable for your mattress and wouldn’t need a separate foundation.
Basically any combination of components that provides a suitable support surface under your mattress that has minimal to no flex, has good center support to the floor to prevent sagging in the middle, has a support surface area that provides enough support under the mattress to minimize the risk of the mattress sagging into any gaps in the support surface over time, that allows some airflow under the mattress, and that raises the sleeping surface of your mattress to a height that would be suitable for you for getting in and out of bed and/or sitting on the edge of your mattress will be fine.
The most common choices would be a steel or wooden bedframe (with or without a headboard that can be attached to the bedframe which is only for “looks”) in combination with a foundation or a platform bed which combines the function of the bedframe and the foundation.
Phoenix