When considering what footwear you should wear on plane you should consider a number of different factor
. First, you will not need to walk around in the shoes for long, and mostly you're just be sat down so it's important to wear shoes that are comfortable just when you are sitting down.
So you need to choose a shoe that will help you to stay comfortable and be happy for a number of hours, on flights from Chicago to Dublin you could be sat in the same shoes for many hours so you need to bear in mind exactly how comfortable the shoe will be. Another consideration is for what will happen if you need to depart in the plane in an emergency. In such situations where you may need to depart through an emergency exit you will need solid footwear, so this must be remembered.
Flip flops may be comfortable and you may be able to kick them off in a hurry but the problem with flip flops is that you will struggle to run or climb in flip flops, so avoid wearing them. A better solution is a comfortable sneaker that you can wear for many hours. You'll also need to walk in the airport to get the plane, so making such a walk in high heels or smart business shoes. Quite simply, you should take something that you can run and sleep in.
Another good idea whether on flights from Omaha to Fort Lauderdale or flights from San Diego to London is to bring travel socks as well. These very comfortable socks are easier to sleep in than shoes, so you can have the best of both worlds. They usually sell travel socks at the airport so you can buy them just before you leave to get your flight.