A nicer room can make your trip a lot better and you can often get one by just asking. Travel+Leisure recommends checking in later in the day to increase your odds, when the hotel staff have a better idea of their room inventory for the night.
Sarah Spagnolo at Travel+Leisure explains:
Hotel managers have a better sense of their open inventory as the day goes on. That means they will be more likely to offer a spontaneous upgrade later in the evening.
For more tips on how to get a room upgrade, check out the full post at the link below.
How to Get a Room Upgrade [Travel+Leisure]