Mellow, Calm, Soothing.
The chord changes at the start are real nice. Well the chords throughout the song in general are real nice. It's actually really good on the Melodic side and there doesn't seem to be anything needed to be added as far as instruments go. If you just wanted to though I would try out Pads in the back, maybe synths to highlight the chords. But mostly I would put pads to fill in although it's pretty full with the piano chords but it would certainly add gloss to it. Like some pads that make ambient sounds in the background.
The drums though, are pretty shallow and you can never have enough percussive instruments. I don't know how this song exactly feels about cymbals but if you added some backward cymbals and things of the light would add a "Epic" feel to it. But it'd be careful with cymbals because those could change the entire mood of not handled gently. Other then that the flow is real nice. I like it man.