Did Satan ever see the glory of God? Known:

The seraphim, possibly among the most powerful of created beings, cover their face in the presence of God:


  Isaiah 6:2 Above it stood the seraphim: each one had six wings; with twain he covered his face, and with twain he covered his feet, and with twain he did fly.


For Christians, one of the highest (if not the highest) privilege of heaven is seeing the glory of God.


  http://www.desiringgod.org/resource-library/books/god-is-the-gospel--2


Question:

Satan -- before his fall -- did he observe the glory of God?
Short answer: We don't know.

Speculation: Yes, Satan saw the Glory of God but not necessarily the face of God.

There are two famous verses believed to describe the history of Satan; 

Isaiah 14:12-15  and Ezekiel 28:12-18.

Ezekiel described him as a Cherub. Isaiah called him "Morning Star". According to Wikipedia Seraphim are the closest to God and of the highest class, Cherubs are the next. According to Ezekiel, the wicked Cherub (Satan) possessed wisdom, beauty and perfection. The mighty Cherub became proud of his beauty which led to his downfall.

According to Isaiah the mighty angel was cast out of Heaven due to his wicked intention to become like God. He said "I will make myself like the Most High". This could mean that Satan, before his fall, saw the glory of God, His power, His dominion, and Satan wanted all of that for himself. Then, the rebellious angel was cast out of Heaven. 

The Seraphs are found only in Isaiah 6:2. They are always praising God and are the nearest to God but they never looked at God face to face, they always cover their faces. Though they are highest class of angels, they dare not look at God. Therefore, we may conclude that even the mighty Cherub (Satan) might never have seen the face of God.