To show appreciation to a great working team I would recommend sending them a Gift Certificate every month. And if you have a Co-op running, why not give them a share of the Co-op, that way you would also be helping them build up their down-line while you build up your own.
This is also a great way to keep your down-line motivated to become successful and to continue moving forward.
This can be done with your whole down-line and not just with your top workers.
All the best