Choosing where to spend a final night when the departure airport is outside the main city

Our flight home leaves from an airport outside the main city. We could spend the last night in the city and take an early train, or move to a bland airport hotel the day before. I hate wasting the last evening, but a missed connection to the airport would be much worse. We won't have a car. What decides this for you: departure time, reliability of the first train, or how much you value one final night in town?