I have been pretty aggressive in refusing to offer a "blended" aka "all-inclusive" rate on my assignments. Hourly plus expenses, and I point out in negotiations that the increases in travel expenses are largely out of my control - though I am willing to do what I can to minimize them.

My current project has a very favorable setup. I work off-site 3 days per week, on-site 2. Hence I fly out Monday night, work at the client Tuesday & Wednesday, then fly home Wednesday night. This really helps on airfares, as I am able to get inexpensive fares by booking those times two weeks in advance. (even though I often prefer to do 4x 10 hr days instead of 5x 8 hr days, it is still nice to be able to wfh so much of the time).