If you'd told hotel guests in 1960 that in 50 years' time the hotel would know the split second you lifted a drink out of the minibar -- or that you could go on a walking tour of the city with the hotel's concierge talking to you from inside a handheld computer -- they'd probably have laughed off the suggestion.
So, while some of the ideas emerging for the "hotel of the future" might seem outlandish now, there's every chance they'll be appearing in the hotel room you'll be staying in in 2030.
Ringtone as roomkey
You can get your airline boarding pass sent to your mobile phone now, so why not your hotel room key as well? There is the issue of the cost of installing a barcode scanner on every room door of course -- that's why a new technology called "Open Ways" is offering a smartphone app which plays a short, unique audio clip which a microphone in the door will recognise.
This way, you could skip the hotel check-in queue entirely and go straight to your room.
The technology could work equally well with 'near field communication' chips being touted by Google and others as ways to make secure payments by swiping your phone near a reader. This is already being trialled at a hotel in Sweden -- Nordic Choice Hotels has teamed up with Telesonaria (the Telstra of Sweden) for the trial.
Meanwhile, Apple has filed patents on its own secret iTravel app to do this kind of thing for iPhone users, as well.
Travellers apparently much prefer the self-service approach than having to deal with front desk staff, according to a recent Harvard Business Review, at least.
Electronic light blockout windows
The best hotels invest thousands of dollars into each room to provide absolute light blockout blinds built into window frames to allow severely jetlagged travellers to sleep the malaise off during the day as if it's the dead of night.
Now, computer screen technology is coming to hotel windows -- a new type of glass which includes a layer of liquid crystal polymers can flip from transparent to pitch black in a fifth of a second, at the press of a button.
We're already part of the way there, with hotels starting to use glass that can flip from transparent to opaque (but not block out all light). New concept rooms at Novotel Bangkok Ploenchit use the technology. "The bathroom is separated from the rest of the room by a high-tech transparent glass partition that becomes opaque at the flick of a switch to either create a feeling of light and spaciousness within the room or provide privacy when needed," the company says.
Whole of wall TVs
Cinemas have successfully defended themselves against the threat of the home TV by offering an unmatched experience of sheer size and sound quality.
People pay the extra money to cinemas because it's an experience. Tourism operates on the same sort of principles -- enticing people to pay for experiences.
We can expect to see hotels offer in-room cinema experiences to guests as ever-larger displays get cheaper and cheaper, and different types of panel technology make it possible to apply them to walls edge-to-edge.
The zero-gravity bed
Australian mattress manufacturer AH Beard has invented what it calls the "zero gravity bed". At about $10,000 a pop, they're not cheap, but then, top hotel brands aren't known for skimping on what's in their rooms.
The "zero gravity" claim might be hyperbolic given the mattress doesn't actually float (or float you) in mid-air, but it does have inbuilt massaging modes and the base can raise and lower parts of the mattress for the most natural lying position for your body shape.
Google at your service
Rather than having to ring the hotel's guest hotline, simply press a button next to the bed and ask, "what time is breakfast served until?"
Google's excellent speech recognition will understand what you're asking, research the hotel's online guest guide in a split second and read you the correct answer.
Likewise, the same Google helper will be able to help you with searching the web for basic information like restaurant addresses and opening hours even if you haven't brought a laptop with you.
The small improvements
Movement-sensing lights that activate when you enter the room rather than requiring you to wedge a room-key into a slot. They are not likely to be accidentally activated by a cat or dog, after all!
Wi-Fi equipped TVs in the loungeroom, bedroom and bathroom with Apple's Airplay technology built in, so you can play your own movies from an iPod, iPad, iPhone or laptop via Wi-Fi.
Wireless room service trays: Hotel corridors littered with the remainders of people's room-service dinners bring down the tone of the place. Why? Because often guests never ring room service to get the tray collected as requested. An "empty tray detection system" uses wireless sensors built into the room service tray to detect when a tray is sitting stationary in a corridor, and dispatches a staff member to pick it up.
Facebook, Gmail and Flickr integration: at the moment, hotel loyalty programs let you register rather 'last century' preferences for pillow type, newspaper delivery and so on. Hotels of the future will be able to remember your favourite web services and display them on monitors around the room. Your Flickr photos, latest Gmail messages and Facebook updates can be displayed in any hotel you visit -- it'll be as easy as signing up to the hotel's loyalty program and linking your favourite web services, just as you do when an app on your iPhone asks permission to post to Facebook.