My husband uses a scooter but we usually take his portable wheelchair 'on board'. However we have cruised with Celebrity and you will not be alone with your scooter. Even with a standard cabin the doorways and corridors are wide enough to ride through easily. The staff are very helpful and usually allocate a seat near the entrance in the dining room so you don't have far to walk. As far as the plane goes, we have friends who take a scooter and they have never experienced any problem providing you contact the customer services at the airline and advise the make, weight and dimensions. I hope this of help, enjoy your cruise.
I travelled the Baltic on Jewel of the seas and used my own portable scooter. I went all over the ship in it and they found a place for me to park the scooter by the side of the lift, but better still I parked it just outside the cabin door and took the battery inside the cabin to charge it overnight. I would advise you to take the scooter on coach trips with you and inform the ship officers that it collapses to a smaller unit than a folded wheel chair. Amanda H. Pampli.
Princess are fine with scooter.