Fly! You get there faster!
We used to use a DVD player, but this year during tax free weekend, we bought her an iTouch and it's great. Small, plays music AND movies AND tv shows and she has games on it. It's also smaller and fits in my purse or pocket, so we can use it in line or at dinner.
When we fly, I always download a new movie or show that she hasn't seen, so that she has something that will hold her attention, instead of something she's seen 100 times. Same with small inexpensive toys, she's never seen them, so she spends much more time playing with them.
Last, food! Snacks are the best. Kids love to eat! Oh but don't buy them a drink before you pass security at the airport. We bought DD a bottle of water and then went through security and she FLIPPED when we had to throw it out. I thought the Vancouver airport was going to go on lockdown from her screaming.

It was at the end of a 10 day trip skiing where she was perfect, so I shouldn't complain.
We let her stay up as late as she wants, as long as she's "going with the flow" and not being crabby, etc. It actually works great, because she doesn't feel like she's having to go to bed, but she still gets tired and wants too.
As far as spending money goes, she's probably old enough to control it herself to some extent, but she doesn't. She asks, I buy it for the most part. We don't buy cheap crap. We talk about what's worth the $ and if she REALLY wants it and will use it. She's the only child of an only child, so she gets a lot of what she wants...sue me.
