Keep the substrates level high! You'll soon find out that things are going to level out as you plant. After filling/planting is done you're going to see that all the soil levels have dropped maybe an inch. Also the high soil level adds much better depth to the tank. Looks excellent. You're on your way. The great thing about nice stable rock structures is that when you're bored of the plants you can pull up the plants and try new combinations without messing up the hardscape very much.
The plants are totally your call. I'd throw some staurogyne porto velho (all time favorite plant) and hair grass in the back and do the rest with a mixed hc, hair grass, riccia carpet.