I think for a truly outstanding hotel it must score very high (93 or better) in all categories at the same time without exception; and that's really hard!

Location and Property: The location should be both beautiful and convenient i.e. close to transportation, historic sites, shopping etc. The property itself should have a unique character and not be mistaken for a chain property. This could be achieved by the building itself, the architectural details, the interior design, the art, the gardens etc.

Physical amenities: They should all be top notch i.e. exclusively high quality items of a certain refinement e.g. linens that are made of real linen (not cotton), carpets made of wool, curtains of real silk. And with impeccable attention to the utmost detail for example the curtain pulls should be practically silent and drawers should have a mechanism that pulls them shut silently. Ideally, there'd also be some local flavor; for example local antiques or particular tiles in the bathroom.

Practical amenities: Those must be very detailed, too. One basic thing that is often wrong is that the curtains and blinds will still let light in. There might not be enough AC outlets, The air condition might not be fully adjustable or make too much noise. The alarm clock might be a nightmare to set. The elevators not fast enough. The whole place should be so well thought out that it works ergonomically correctly. Another example would be that there should be a long shoe spoon. Or a switch that automatically turns on a light as soon as you open the door. And a kill switch for all lights by the bed and by the door.

Safety and security: There should be sufficient safe space i.e. the safe must be big enough even for a 17" laptop or a 12" tele lens. Nobody gets even into an elevator if they are not a guest or accompanied by the guest. Good video surveillance, full background check on ALL employees.

Service: It should be so individualized and so attentive that you feel like a prince(sse) but without feeling like your privacy is invaded (Prince of Zamunda's little prince is now clean, your highness). This is a very difficult balance to get right. I have often been addressed by my name even in big hotels only hours after I checked in, and by personnel I had never met before. That is absolutely impressive. It is super discreet, yet highly efficient and always friendly (not just polite). I need to get the impression that I really matter to these people and that they like serving me. Any eventuality must be prepared for. Sir Rocco Forte was once quoted as saying to one of his managers that if a guest asks for a camel, the answer should be whether the guest would like his camel alive, sliced or cooked in a particular fashion. Forte said he never said that, but I think this is just about the right attitude.
I also second the generosity suggestion. Charging a guest $10 a day for internet access when each night costs upwards of $500 is ludicrous. Instead the hotel should have an IT expert on hand 24/7 who will come to my room if I have any difficulties. OJ, water and coke from the mini-bar should also be free of charge. I also like to receive polite unsolicited advice. I like to hear something like: "Mr. R., I know you are very interested in opera. XYZ is playing tonight and I can arrange for really good tickets if you wish." Or even a well-meant warning in the line of:"I will gladly reserve a table for you at restaurant x, but the quality there has not been very consistent lately. Would you like to hear my suggestion for something similar that I can recommend whole-heartedly?"

Perks: Depending of how good a customer I am I would expect stuff like being picked up at the airport in a limo by a chauffeur who comes only for me, at no extra charge (I don't need a Rolls, the S-Class will do). The Krug replacement champagne in the post above was a NICE gesture, I must say. Also some very exclusive amenities are installed for frequent guests at certain hotels (Ritz and Bristol in Paris come to mind). For example one can have one's own mattress and bedding put in the bed. When one leaves, the mattress and bedding are stored by the hotel free of charge and put back in place upon one's return. The same is possible for a wardrobe. A luxury hotel where you are a frequent guest will store personal and clothing items for you and put them in place so they are ready for when you arrive, freshly pressed and laundered with shoes polished.

Finally, the guests should be eclectic but classy. I can deal with seeing an occasional pimp if it's a high class pimp in very pretty company.

It should just be a place so charming and perfect that you wish it was home.

Till