I agree if travel services are implemented than they should be in real time, with option to skip of course, but if not skipped than maybe there would be the possibility of having to fend off an attack along the way, etc. etc.
I also posted this in another thread--seemed applicable here, because it is basically my idea for realtime fast travel.
Since it is Skyrim, and since this could loosely fit into the established 'lore' and culture of that society, I think the most practical form of fast travel that they could implement in the game(besides caravan, mammoth, etc.), is to utilize some kind of ancient Thu'um transport, by shouting you across the map. Perhaps scattered throughout the game world, and in each major city, there could be small mystical ruins or ancient pieces of architecture that had been magically infused(enchanted) ages ago by the most powerful 'tongues' of old, with the ability to transport people by shout. Something similar to the size and design of the Ayleid Wells in Oblivion, but with a nordic style, and maybe each could house a large crystal at its core, which when struck with a rod or activated with a spell or something will ring and then reverberate with the sound of the shout, carrying whoever activated it, wherever they wish to go. Whats more, is that since its already been stated that the cities won't be sealed off from the rest of the gameworld, they could, in theory, create an animation in which you dissolve and become one with the shout, speeding across the land with the sound and the wind, before re-materializing at your destination.(WOULD REALLY MAKE FAST TRAVEL SEEM MORE LIKE 'FAST TRAVEL')