I understand that everyone has their reasons, but I actually do think some reasons trump others.
For instance, DS is older now, but when he was a baby, I needed to sit next to him, while I only wanted to sit next to DH. If we had planned 3 seats together, but circumstances had interfered, scattering us far apart would have been a major problem, but splitting us 2 and 1 would only have been a minor annoyance.
If importance falls along a scale even within one person's reason's, of course it would among a bunch of people's. (And I get that some of those more important reasons are medical issues for adults, not just children!)