In your case I do not see that you have much choice. If it is required for you to work on a public holiday then the pay due to you is as agreed when you signed up by the company. I would see it as being mostly out of your hands as I’m sure the company has a pay structure and you would fall into a certain band. In addition, it is most likely company policy as to who gets paid what on normal and public holidays. So, I would not feel bad about doing little and getting paid double.
Maybe I would try and see what else I can do for the company whilst waiting for calls? Some initiative to improve things around the workplace?
Regarding my question, I organise my flights and accommodation myself as I work for myself. Yes, if I did the trips at different times both clients would be paying full expenses in any case. Thus I do not see it as their right that I should only charge them half the costs if I combine the trips into one.
But, if I ask myself what Jesus would do I guess the answer is pretty easy. He would charge each client their due which in this instance is only half. It will also leave a positive impression on the client if you explain why you’re only charge them half - which could go a long way for my client relationship.
Guess I answered my own question?