Here are some suggestions I think can help with that.
myCharge – nearly anything they make
A fast fast wall charger
From nearly dead to 90% in less time than it takes to braid a yak. No, I don’t really have a good time estimate here except to say this is the fastest QQC3 charger I’ve run across.
If you can get a wall plug at an airport you can be charged pretty quickly.
In general disable these. If an app starts, is killed, and restarts, and is killed over and over you’re just running the processor nonstop.
I’ll add a caveat though that if you know what processes you can safely kill, you can save a bit of juice by killing spyware, Facebook, and things that really have no business running in the first place.
Sleep through the holidays
One thing you might want to consider is rather than dealing with manufactured guilt to go and be somewhere during the highest traveled/most expensive/most flu-ridden days of the year you could just Skype them and visit when it’s cheaper.
Whiskey or bourbon
Not only good for calming the nerves, but you can also use it to charge your phone. No, I’m kidding. I’m sure there’s a way but file this under the sleep through the holidays thing.
Lower screen brightness / timeout
Drop the brightness on the screen while traveling to squeeze a little more juice out of your phone. If you’ve got extreme power saver, kick that on when you’re not actively doing anything that requires a data connection.
Uninstall a lot of stuff
If you’ve got games that are showing as running in the background chances are they’re data mining and phoning home occasionally. While having a program on the phone doesn’t use battery, having the program initializing and then loading ad code in the background while reporting things such as phone activity do.
If you don’t need that old game, chuck it. It may not improve battery life but it at least lowers the clutter you have to scroll through.
Pre-load map areas
If you’re going to be traveling with Google Navigation, pre-load some of the areas you’ll be traveling while you’re on WiFi. It’ll take up some additional storage space but should save having to pull the data down at much less energy efficient LTE/3G speeds.
Map areas expire eventually and the space is returned to the system, or you can delete them after you’re done with them.
Bring a book you addict
Grab a book. Not an e-book. I suggest The Martian. Really pretty awesome.
Remember to keep your battery charged, not just the phone.