Backyard redo - do following floors need a concrete base?

[John Collins]

I am looking to install flooring in a backyard. Some ideas are above - one is a brick base, one is a slate type substance and one appears to be tile. I know porcelain tile with mortar requires a concrete slab to go on top of, but what options do I have if I do not want to install a concrete slab yet want the ground to remain fairly rigid and solid enough to have chairs, tables, etc? Not going to be a deck in addition - this will be the main sitting area. 

I have already demolished the concrete which was poorly installed and caused the tiles on top of them to move around, pop out, and generally be dangerous. 

There will be no firepit, only a sitting area!

Also noticed houses remain a bit cooler in the summer without huge slab of concrete outside.