Teen - love your Santa quilt. I've got the same scallop ruler but have not used it for a border yet.
My thoughts on binding- I love the way it looks unbound, so I 'd lean towards the same color as the border, either the same fabric or a solid green that matches. I think gold would bring another element in that isn't much there already in the blocks (unless it just does not show in the picture) They have a lot of dark cream, which isn't quite the same as the gold in the border. Gold would look great with the border fabric, but I think it would make the border look less tied to the center. And I think cream would dilute the bold look of the dark green frame, and I like that bold frame look.
However, colors on monitors can be very deceiving, so I might think something differently if I saw it in person.