1.People [who wish] to go on the tour have to book in advance.
2.People [wishing] to go on the tour have to book in advance.
【分析】
第一个句子中的用法是最地道并且最常见的,用定语从句描述people.
第二个句子中用wishing在语法上讲是没有问题的,但是太侧重于语法了,不生活化.