If you are taking your dog (I'd never consider leaving mine behind), the best thing you can do is get the dog used to a crate if they are not are already crate trained. This would make the whole experience a much more pleasurable one. My dogs see their crates as their safe den, and will take themselves there if they're unwell or have a sore paw. They are quite content in being locked away in the crate, and as such, I don't believe a long journey in one would be stressful for them. They are calm in their crates.
You also need to make sure they are on top form from a health perspective to get through the journey as well as possible - if they are overweight, put them on diet! If they have health issues, research and make a decision on what is best for the dog.
If you're not prepared to put that sort of effort in to your dog, then in my mind, the dog is probably better off re-homed to a loving home.
Flying with dogs internally is common place in Australia - we take ours on holiday with us. $75/dog/each way and we find dog friendly holiday accommodation (some of which is absolutely gorgeous) makes for a fabulous holiday.
And there are plenty of rentals who allow dogs - as one agent said to me "dogs tend to do far less damage than children" - people are much more geared to it here than in the UK.