I have an Airhawk cushion on my motorcycle and one one of the things I find best about it is everytime I stopped for petrol I'd let a little air out, or add a little air. It took 10s and gave me a different riding position for the next few hours. I can spend a lot longer in the saddle with it than without. (Speaking of saddles, I plan on trying it next time I go horse riding too, though I don't know what my queue will be for adjusting the volume of air).
Interesting! I used to have a Morgan car, and the seat was a blow-up to which I'd add or remove air to change my position. It helped avoid discomfort on long-distance trips.