My ceilings are 14' and I am 6'4" and I work in commercial construction. I can reach the trusses on a 10ft ladder. But a 12' is much more comfortable and safer.
We have 14 foot ceilings in our living room and a 10 foot ladder. I am 5'10" or so and can just reach the two smoke detectors and can unscrew the recessed light bulbs but it is a real stretch. I generally use one of the long poles with an attachment to change the bulbs. I store the ladder in the garage, but it is really quite big, particularly compared to the two six foot step ladders and the extension ladder.