Thanks for all the congratulations! :) 8+5 so early days... sure it will sink in by xmas...
I (obviously) only have experience with flying with one child, but Lukas and I did clock up a respectable amount of flights during his first year. IME, the "worst" time to fly is when they're at the crawling stage, because you can't let the loose in the airport/on the plane, but they're desperate to be on the move and certainly don't understand why they have to sit still. Also, at that age they're only moderately entertainable by ANYTHING.
Apart from that short stage, I did actually find flying doable (with one, not sure I'd attempt it on my own with two...). My top two tips would be to pack a sling (Lukas travelled in his even when he was 15 months, because it's the easiest way to transport them around the airport and onto the plane whilst managing luggage etc) and, although people frown on them, reigns. :D
Not really usable on the plane, but definitely helpful in the airport. You can push a trolly with one hand and let them run around while controlling them with the other.
And yes to a few new toys / books to keep them entertained... and most definitely at least one change of clothes for mama and DC, you WILL get covered in something, whether it's food or poo or vomit. :)
(On that cheery note, I shall end.)