Your question is a good one....but involves a lot of decisions...
Firstly decide how many activities you want to furnish for.....

I suggest a reclining group...maybe one or two chaises...

A dining area( close to house and kitchen)

And a group seating set(couch..chairs..ottoman,etc)

These should all be comfort first and lightweight enough to move easily...

Also area rugs are my favorite in outdoor settings as they make it inviting and more comfortable

If you can ....place your seating so something is always in the shade during the day

A few big decorative pots with plants can help define you areas as well

# missed the small photos...you have all the ingredients for a great space...as for the zen part I would focus on large beautiful pots with statement plantings ...area rugs...and maybe a pergola for shade and to create an outdoor room feel for your group seating...maybe with one or two walls of very loose open squares to further define the space(such as 2' squares in a wooden grid)

As i see your space, what i'm not hearing is a waterfall...nor trickling of water