She is a good sleeper so I think I should aim at night flights outbound from MEL or SYD.
Did you get her her own seat Boris spatsky?
Took our 3 in J a couple of times with no problems.
I have experienced more noise from, previously described above, people laughing loudly as they've destroyed their hearing and have the volume way up on their headphones than noisy under 5s.
The most common cause for noise (after irresponsible parents) is Eustachian Tube problems.
The younger you are the more severe the pain. Imagine a hot knife being shoved into your head slightly behind one or both eye sockets. It would make anyone scream.
There is a simple solution to the problem which is caused from the change in air pressure. In the ancient past (a little pre-internet as my children define it) most airlines gave out boiled sweets to passengers. Chewing, swallowing etc will help equalise the pressure as the plane takes off or starts to lose altitude. The gradual decrease in altitude can catch a parent unawares vs the take-off. The pain is just as bad for babies and toddlers though. Many parents will put it down to their child being tired after the flight.
For a baby/very small toddler make sure you have a bottle (or BYO source) for it to suck on as soon as the plane starts to take off. For the loss of altitude - have a low flow teat so the bottle does not empty too soon.
For toddlers that can safely chew then have a ready supply of something suitable for them.
It is absolutely the worst if they have a cold/flu.
For toddlers more switched on (and others) get them to squeeze their nose tightly between thumb and finger. Then get them to try and blow air out of their nose as hard as they can GRADUALLY. Not like trying to blow up a balloon with their nose (good way to distract them on the ground) but gradually build up the pressure.
Try doing it yourself right now if you haven't heard about this before. You can feel the difference at ground level.
One other tip - you can always practice getting them used to the more cramped sleeping by putting some hard long object in the bed/bassinet in the lead up to the flight to simulate the seat, armrests etc. A large collapsed cardboard box folded up several times (and duct taped up) works very well.
Depending on the child's size was our deciding point on their own seat. If too big for bassinet on plane then buy the seat so both of you can sleep.