Looks nice.. love rock work. We have lots at the office gardens, lots of big ones with the thought that folks will use them to sit on etc. They do too. I would recommend blue oat grass. I have it the work garden and home. Planted right up against the rocks and it softens the edges beautifully. Doesn't need trimming either. Grows about 3 feet tall and is open growing and survives my zone 3 landscapes.