Eyes

Most of the time I look at the score, which unfortunately to often is down, so I play to MERI.

I like to close my eyes and get more of the feeling that I am being absorbed into the music (or vise versa).

of course the score takes care of the eyes, but when playing without score, i tend to either close eyes or do the half-closed eyes on the floor just ahead of you thing, as in zazen. as Jarle Jivanmukta said, less distraction, easier to focus on the piece and internal processes.... unless outside in pretty place, then eyes just on horizon to take it all in!

Nice!

Eyes can distract when reading a sheet, so it's good to memorize the songs, so we can get deeper in/with them!

When playing long tones, sometimes I like to make it togheter with a common meditation technique which consist in "look" the point between the eyebrows, with closed eyes! It puts me high in just a few notes! ehehhehe

When I practice, I pace around counter-clockwise in my kitchen. I don't really look at anything. I look a little bit at the floor but I do not notice it much. I like to let my other senses have more time than my eyes.

One reason I wanted to play a shakuhachi was to not use my eyes so much.

I find the best use of the eyes when playing most instruments, if not reading music, is to unfocus the gaze. To do this focus on a point in front of you, and then unfocus so you can see above, below, and all around equally. I find that when I use that technique my ears follow suit and open up to take in a wider scope of the sound spectrum.
I like to do robuki walking around the house with this technique, and at the same time cultivating the intention of blessing the space with the sound. It's a deep meditation.

When performing w/o a score in public I tend not to look at people's faces unless I am wanting to get their attention. In that case I usually look down a bit unless I am playing dai kari, then I usually look at the ceiling/sky. Where you look tends to be where your head is pointed. For this reason I try to look as straight forward to the horizon as possible, even when practicing, but am not rigid about it. My eyes just float around at whatever otherwise- I am not usually conscious of what I am seeing. I will admit that sometimes my eyes are watching TV.

In Tai chi I look down a far valley, when I am trying to play the shakuhachi I look to a far mountain top. This has helped me to get over the initial problem, which I haven't completely solved, of playing flat.