3.3 m = 11 feet. 3.5 m = 12 feet.

Optimal ceiling height depends on the room size. The bigger the room, the higher a ceiling it should have.

Brightness is strongly dependent on window size and location, as well as orientation. Ceiling height alone will never create brightness, but it can work with ample, high windows to improve brightness.

Beautiful openness depends on design generally, including sightlines (interior and exterior), ceiling style, presence or absence of headers, and the balance of color and mass in furnishings and surfaces.

Echoing depends on the relative orientation of surfaces, angles, planes, and sightlines....only slightly on ceiling height.

Ease of air conditioning depends on insulation, airflow, routing of air circulation, sizing of A/C equipment, location of ports and returns,and overall volume of air to be treated.....again, not to first order on ceiling height.

Basically, there is no clear relation of ceiling height controlling the factors you are interested in. Creating those factors is much more complex, and I would not want you to think that mere ceiling height could control the outcome.