1/ Day Trip
You will spend at least 4 hours on the boat cruising the bay if you are just going for a day boat. As it will take almost 4 hours to get from Hanoi to Halong Bay and another 4 hours to return to Hanoi, so it may feel a bit disappointing to spend more time in the shuttle van than on a boat if you choose to go with a day trip. This option is extremely tiring for children so it is not recommended for families or groups with children. On contrary, you can consider it if you are a healthy traveler or for a budgeted trip.
2/ 2 Days 1 Night
If it is within your budget, Discover Halong would strongly recommend choosing an overnight cruise as things become much quieter and less crowded in the evening and it is nice to have more time to move around the boat and engage in more activities.