I'm on a pleasure trip.

我是观光旅行。

An excursion, typically a pleasure trip.

这是一次非常愉快的旅行。

Sincerely wish you have a pleasure trip.

衷心祝愿您旅途愉快。

This is meant to be both a business and pleasure trip.

那就是说既处理业务又游览游览。

This is meant to be both a business and pleasure trip for you.

也就是说，你既要处理生意又会四处游玩。