crikey, my kids are well travelled. We took our son to Australia when he was 18 months old, the flight on the way out wasnot too bad, he wanted to walk round the plane!
My daughter turned 1 when we were in Sydney, and then we went back there when she was 2. Now we are off to Australia again for the 4th time in 6 years, which makes this my sons 4th time there and my daughters 3rd time there, and she will have her 4th birthday in Sydney again.
So far my kids have been to Spain, France, Singapore, Dubai, Hong Kong, Australia and will have Kuala Lumpur when we go outthis year.
If you are weary of travelling too far on a flight with a child that age, try not too have a flight more than a couple of hours long., We tend to get flights leaving in the late evening then there will be more of a chance for the kids to get some sleep on the way.