Let them eat cake!
Does one of your clients or customers produce a product you could use as an award? If so, order some for your next recognition event. We used Sara Lee cakes as a team thank-you and people loved it!
The benefits of this approach are twofold: your employees get the recognition they deserve, as well as a subtle reminder of the importance of your valued clients.
(FYI: If your client is BMW, you are going to be one popular person!)