You must decide if you want the doors to be featured in the room and how the doors relate to the rooms.

For normal swinging doors a 7 ft height would allow both the doors and the room heights to feel generous without making a feature of the doors. Taller doors can become narrow features that can detract from the room height.

Wider openings might be more appropriate as features and therefore taller than the normal swinging doors depending on how you want the rooms to relate to each other.

It is important to study the walls of each room rather than adopting arbitrary rules of thumb.

We have 9' ceilings and some higher ones (to 16'). All our passage doors are 3 X 7, with four inch casings.

We have 9' ceilings and standard height doors, I think they are only 6'8" tall maybe? They look fine to me and I notice those things.

we're having 9' ceilings throughout and are planning all standard sized doors. the space between the top of the door and the crown, and the top of the cabinets and the crown, are one of the things I found most appealing about 9' ceilings.

I'm in the same group: 9'+ ceilings and standard 80" doors. I think taller doors would look out of scale and pretentious in our house. My view is that you don't need taller than standard doors unless Dr. J is a frequent guest...

9 ft ceilings as well over here, our's are also 80".

I'm also facing this decision. Would love to see pictures - thanks!