wish you enjoy your china travel.
i belive you have a good travel in china.
第一个比较好吧。。第2个是字面翻译,第一个比较口语化。
I believe that you will have a wonderful trip in China.
I believe that you'll have a nice trip in China.
I believe that you will have a nice trip in China.
I think you're going to have a marvelous trip in China.