Is a day trip from Dubrovnik to Montenegro enough?
A day trip from Dubrovnik can show you the bay, but it compresses Montenegro into traffic, borders and one photogenic old town. Stay overnight if the country is more than a checkbox.
Answer
The Dubrovnik-to-Kotor day trip is popular because the map looks easy and the reward is obvious. It can still be a good choice for travellers who are already based in Dubrovnik and only want a taste. But the trip is shaped by the border, the road and the limited hours left once you arrive. You are likely to see the bay at its most compressed, not Montenegro at its best. If Kotor, Perast, Budva, Lake Skadar or the mountains genuinely interest you, one night changes the whole calculation.
Recheck before you go
Entry requirements can change. Check the current rules before you travel.