I think luxury hotels are about the guests' time. A true luxury hotel, IMHO, is one where when you walk into the lobby it feels as if you have left the outside world, outside. Inside the hotel is calm and serene, almost a timeless quality. Not all luxury hotels are like this. But luxury hotels save you time by putting all the options at the guests' fingertips. And, for that time saving convenience, guests will be charged (dearly) for it; many are willing to pay. For example, at Four Seasons George V in Paris, room service is 24 hrs without the annoying cover charge with a larger than usual selection of items available (not just sandwiches), concierge and business services 24 hours, 4 hour laundry and 1 hour pressing 24 hours a day, complimentary shoe shine, etc etc etc..... Luxury hotels tend to give you more personal space (not always), little extras like fresh flowers, fresh fruit, etc etc

The "value" comes knowing that everything will be taken care of; excellent service, if you are a regular, your preferences will automatically be instituted in your room (sheets tucked in, temperature warm or cold, classical or jazz on the radio, complimentary sparkling instead of still water bedside, knowing that you tend to sleep on the left side of the bed so that is where your slippers and mat will be placed, you prefer diet pepsi so the minibar is stocked with diet pepsi's, etc) and the Concierge staff will take care of all other details. At the Four Seasons George V, any postcards or letters we sent were not charged to us, nor were any of the numerous faxes we sent all of the world were charged to us either. Any item we needed, say La Maison du Chocolat chocolates, would be purchased for us, and charged to our account, but with no extra "Valet" charge.

Lots of these things most travellers do not want or need most of the time. For some, these services are indispensable. I guess it depends on what kind of traveller you are, whether on business or leisure, you prioritise whether to spend the extra (sometime not much more) over a business hotel or whether the business hotel is adequate to your needs.

Sorry for such a long post. My £1.50 worth!!
Cheers