Here are several options for using "safe travels" in a sentence, each with a slightly different nuance:
- Formal: "I wish you safe travels on your upcoming journey."
- Informal: "Safe travels, and have a great time!"
- More descriptive: "May you have safe travels and a memorable trip."
- With a specific destination: "Safe travels to Paris; I'm looking forward to hearing all about it!"
- Empathetic: "Safe travels; I know you've been looking forward to this for a long time."
The best option will depend on the context and your desired tone.