Joe: You make a very good point, but keep in mind that you can't "mix and match" how you go about claiming unreimbursed expenses. So your total outlay would have to exceed your total per diem and the total allowable M&IE rate before you can claim it. Maybe I'm too cheap, but I don't spend enough on layovers to make a difference. I can easily see how this might be the best way to go for some.

Pilot 772: Great info. One has to check if it's better to go city by city or the combined rate. Domestically, it's close to a wash. Internationally, I think you'd be better off going city by city.

I think the key thing is that you can do your own per diem calculations. It's not rocket science and most pilots can do it in their spare time.