E.P.
As a cake decorator myself, I would recommend doing a round, two tiered, cascading effect and instead of any kind of decoration/piping on the side I would use the words going around each layer. The only piping I would do would be the seams at the base of each layer. When it comes to the colors, if you are still fond of them, I would recommend the wedding colors and since the ten year anniversary in diamond I would use edible diamond dust for a little shimmer. All in all I would keep it simple in order to make the words stand out. I love the saying by the way and congrats on the Ten Years together. I hope you guys have a great time.