I would put down "sleepers" first, then deck boards. There is bound to be moisture trapped in there to some degree no matter how you do it. By putting 1x or 2x pressure treated boards directly attached to the concrete, 16" on center, you can establish some air flow under your deckboards in order to keep them from rotting or cupping. Generally, high quality pressure treated decking won't rot with this type of contact, but if the bottom side isn't allowed to dry after rain then your boards will likely all end up with the edges cupping up and/or weathering and degrading prematurely. The only problem with sleepers is how do you clean out under them every year or two. If dirt and leaves etc. collect under the boards then you will have a moisture problem again.
Remember that you need to raise up your stair treads the exact same amount as the main deck in order to keep the risers the same height. Then, you may be left with too high a bottom step.
There are many ways to do this project and I'm sure that others will chime in.