Looking at the first below I'd say, to be on the safe side, the bedhead should show half to three quarters above your tallest pillow. The second photo I believe shows too much bedhead.

You can have what ever ceiling height you can afford. But also think of what height windows, internal and external doors will be. What heating and cooling system you will install. What window treatments will be required for extra height windows, etc etc. Our double storey home has 2700mm ceilings throughout with 2400 doors and windows. This height is ideal. A gable ceiling in the living and dining areas, I think, has more character than a 5 metre ceiling in one room. Have 2700 ceilings throughout the remainder of home. Depends on the aesthetic you are going for, to what the design could be.

Is there a particular reason you want to lower the alfresco height ? If I had to make a choice , I'd almost prefer to go for 2.7 indoors , 3 metre alfresco , because thats where you want that open feeling , the luxury of space and height , moreso in in an alfresco . As far as being noticed , the only time it wouldn't be too noticable ( IMO ) is if the alfresco floor was lower than the house level -- if you step 'outside' through a standard or sliding door , and the roof feels lower , I suspect you would notice it . That , afterall , is why you go for a 3 metre inside height , to feel open and spacious .

What height window and doors are you proposing. If 3 metre ceilings then 2400 doors and windows would look better. This will then add extra cost for window treatments. Also in the kitchen, with a 3 metre ceiling, where would you stop your overhead cabinets, would you have them to the ceiling? Or standard height? I personally would do your pitched ceiling in living area, and 2700mm everywhere else. This will add extra interest with the change of ceiling height. 2700mm are a good height.