I am Hilton Diamond and often get upgraded. But that is part of the deal of being one and staying in their hotels all of the time. My tips are: 1) Definitely do your research in advance - you are wasting your time in some places if they don't have better rooms (for example, Hampton hotels, Hilton brand, are all the same) 2) Fabulous upgrades are, in my experience, better suited to one large bed, I often travel with my sister or my daughter, and we definitely do not want to share a bed, however large and luxurious the room is 3) join their loyalty club if they have one, usually free, probably helps 4) Email them or add notes on booking. Once you are there, unless there is a real issue, they will have pre-assigned a room, reversing it isn't an issue for them if they have plenty of rooms, but they are less likely to do it if busy and on a whim, also they generally go "one room grade up, not suddenly a suite" 5) If you have a reason, mention it, may work, may not, but worth a go. Chancers saying it is a special birthday watch out (esp abroad) as they get your passport. It actually was mine when in Thailand (and no, we did not ask for upgrade, nor pointed it out) but they knew and made a "lovely fuss" at breakfast time cake, fruit and sparklers, all staff singing, Excruciating, if nice. 6) complaining about non-real-issues in your room will get attention, and even a room swap, but sometimes lesser room than you had. I have had some very odd but excellent upgrades in my time including a two bedroom penthouse suite, lounge, full kitchen, full dining room / drawing room, 3 TVs, two terraces, and glassware to suit a party of 12. Fridge full of drinks. Mood lighting. I was there for work and literally went from the desk to my bed, and used the bathroom twice and had a bottle of water. I might have well as been in a single room in a crap hotel ! You never get them when you want them 😂 good luck though, shy bairns get nowt x