I frequently find with BKK taxis that the drivers are frustrated F1 drivers and the rear seats almost always do not have seatbelts, so taking a Limo rather than a taxi is also about safety not just comfort. In addition you get the little taxi driver scams which are well known to regular visitors to the City but may cause others issues. When all is said and done the AOT cars aren't an awful lot more expensive and much nicer so I would take that as the cheap option, or for more comfort take the hotel Limo.

I go out of my way to book a hotel Limo as a marker of intent. The intention is to say to the property, "hey I don't mind dropping a fair amount of money at your property over and above my room rate" (whatever that might be). I then potentially seriously revise this approach upon arrival depending upon the room allocated, or continue to spend freely if I feel I have been given a decent room considering status, special events etc. Better properties seem to "get" this approach, those that don't see very little spend from me on their spas, bars or restaurants.