I know that there is a "rule of thirds" for some interior design considerations. When wallpapering the bottom, or top of a room and painting the other portion, it looks good with the bottom third being a dividing line. Applying this rule for wall sconces without a table underneath, you could use two thirds. This would put your sconces above 6', but on a ten foot ceiling it may balance well. If the intent is to illuminate the booth, try one third the distance from the table top to the ceiling (120"-34" = 86". One third of that is 28" above the table).
What I have done in this type of situation is use graph paper and work up some sketches. You get a pretty clear picture before starting!
