Business trips, whether they be domestic or international, are more and more common these days and are a good topic to discuss. After all, most likely your students that go on business trips need to speak English! You could ask:
Do you go on business trips at work? Where?
What are the advantages/disadvantages of business trips?
What advice do you have for somebody traveling for business?
Where would you like to go on a business trip? Why?
What do you think is the future of business trips?