Two different sheva brochos I attended have really stuck in my mind.
1. American theme, tableware was all red, white and blue. Waiters/waitresses wore Uncle Sam Hats and served typical American menu.
2.Smiley Theme. Black tablecloths centre pieces made up of a large boquet of yellow smiley balloons. Walls were decorated with smilees. It made such a happy atmosphere sorry I dont remeber the menu!