This is a bit late but seeing that we will be taking our kid on a year long traveling experience, I have to say that conditioning is key. Both my wife are avid travellers and have been even before we got together. We both lived abroad for several years and have traveled a lot in that time as well as for a couple of months each summer. That being said, when we decided to have a kid, we wanted to try and give the little guy the passion to travel by exposing him early. His first trip was out to Halifax when he was several months old to visit the in-laws and that was actually not as bad as we thought. He is 4 now and has been on a plane something like 25 times or something already and just gets in and has no qualms or issues (knock on wood) other than always claiming the bloody window seat! We fly out that way at least once to two times a year.
Our first major haul (as if 6 hours to Halifax weren't long enough) was to Europe when he was 1. We were there for almost 2 months and went to the UK, France, Portugal and Spain. At 1, it was a lot of carrying him around and visiting spots that he could crawl/walk around and eat. We were pretty flexible with his sleeping/eating routines and it dictated our day to day activities quite a bit but we were still quite flexible and stayed out past dark many times. It did mess with his sleep schedule but we were able to get him back on track. We still did what we wanted and visited many of the popular attractions but the biggest difference for me was that I was not as hammered as I used to be on trips!
On his 3rd birthday, we headed back to Europe for about a month a half but headed to Turkey, Hungary, Belgium and the Czech Republic. Once again, the same type of trip was expected and he was a lot more fun. He slept when he was tired and that was sometimes when we were in the middle of a tour or traveling from tourist site to tourist site. Again, we were very flexible and abandoned some of this routines but again, made them up when we got home.
His 2nd and 4th birthday were trips to Halifax and when he turns 5 in July, we will be off on our year-long world travel starting in South America, heading to Africa, then Asia, NZ/Australia and then back to Europe where my wife wants to really hone her French speaking as well as expose him to some of his own learning. Our trip is not yet set in stone and we will most likely make some adjustments but like I said, the conditioning to travel started early even when we are taking trains, planes, cabs or walking, he has been pretty good. Waiting in line as well as delays, he's managing them quite well like when we were in the Toronto airport and our flight was delayed for 4 hours, he was awesome!