Any of the tall gras variety, they grow fast & spread so don't plant too many. Ferns are also a good choice. I suggest tall plants at the back then maybe astilbe in the front with maybe some variegated small hostas. Good luck.

Me, I would have same height all around. Maybe hostas & then add annuals for color. I like the 2 toned fence.

I'd like to see Bougainvillea on the fence and maybe Catmint or Lavender for around it. If you want it to be really simple then plant a short Sedum.

Here are two different fountain styles. I love adding rock around fountains then bringing in color with plants.

Love Eye of the Day's idea of adding rock around the fountains - keeps your maintenance requirements way down as well!