For the flight (assuming there's a flight) (And also, some of these will be less pivotal if the flight is less than 2 hours):
1) Fly direct if possible. Connections suck. I mean that.
2) Pack two sets of extra clothes, a crapload of wipes, and three more diapers than you think you'll need. (Don't forget to allow for the pre & post flight time too - getting to the airport, pre-boarding, customs lineups.... etc.)
3) Pack an extra set of clothes for you too, if there's space. You think I'm kidding. Don't say I didn't warn you.... You might not ever need them. But if you do - you'll be glad to have them.
4) Cut 18" lengths of diaper genie liner to put used diapers into, tying both ends up 'candy' style. You might end up seated next to the 'bathroom', but even if you're not, leaving a stinky poopy diaper exposed to the air we all have to breathe is cruel & unkind to your fellow passengers. Bring lots. They pack small. You can also use them if some clothing gets soiled, wash the clothes, store in plastic tube, deal with at destination.
5) Snacks. Lots of snacks. Stick with the prepackaged, purchased kind - customs & airlines aren't very sympathetic sometimes.
6) Formula/sippy cups/bottles to help the kid's ears pop. Buy juice & bottled water once you are through security.
7) Some soft stuffies, some quiet, non-battery toys, & some stickers.
8) A couple blankies - for covering up while napping, for playing peekaboo, for last-minute togas, and also, for wedging under/around your body as you attempt to make yourself into a crib/playpen/jungle gym. (There is something about travel that makes my child blast through diapers & clothing at an unanticipated rate.)
9) Disposable plastic pads for changing diapers on. As well, not all planes have change tables. If you can teach your child to have its diaper changed while she's standing, this will make your life soooooo much easier. Otherwise, the disposable plastic pads are a lot better option that putting your husband's jacket onto the floor.
10) For clearing security, customs, boarding, and anything else official: One adult takes all the paperwork, one adult takes the babe.
11) Unless you baby is really light, and happy in a sling, bring along a collapsible umbrella stroller. Easier for cruising through airports & wrestling with luggage, and worth the hassle of collapsing it to send through the Xray scanner. (Also a portable restraint device, if it's got a seat belt.)
12) All your liquids have to be less than, um, 120ML, or 2 ozs. But check that! These things change! And they all have to fit into (and be in) one Ziploc baggie for security screening.
13) Depending on flight time & your technological savvy & equipment, load the kid's favorite movie into a video IPod.
14) Ziploc baggies, Ziploc baggies, Ziploc baggies. I had one full of liquids, one for diaper changes, one for snacks, one with toys, one with my knitting, one with the iPods, and a couple spares.
15) A full bottle of each OTC med that your kid might possibly need - for Amoryn, that was Baby Tylenol, Gravol, Antihistamines, & gripe water. Just in case though! Don't give them all to her!
And on the topic of drugs, if you are planning on drugging your child (and to paraphrase Hunter S. Thompson, I hate to recommend it, but it always worked for me.): Gravol is something that isn't supposed to be given to kids under 2 - but - you could always check with your doctor. There's also the option of antihistamines - also check with your doctor. At any rate, if you think you might, the plane isn't the first place to try it - some children have an opposite reaction, & instead of calming down, they get wound right up like they're on speed. Talk to your doctor, and try it at home first.
A) Maybe check into getting a hep shot for the kid - to prevent the kind of hepatitis that you can get from food. For Am's we had to go to the travel clinic, not a huge deal once they're one, but you have to talk to them a lot if your child is under 1. (Although they do provide that vaccination to newborns in other countries of the world, and hello? Hep is not fun, and have you ever met a baby that doesn't put EVERYTHING into their mouth?)
B) Think about staying in an all-inclusive - yes, maybe less great food, but quick & easy access for hungry kids, and our theory was that it would be pretty tourist friendly, so no worries about food poisoning.
C) LOTS AND LOTS OF SUNSCREEN. And hats. And those awesome sun blocking swimsuit jumpers from MEC. The baby bikinis are cute, but useless. And I suspect a sunburnt infant will be worse to deal with than a colicky one.
D) The place where you are going might have a baby stuff rental business - check ahead. We rented a crib, a booster seat, a diaper genie, & a car seat while we were in Hawaii, and it was excellent. (Akamai Mothers, if you're headed to Maui.)
E) Book a room with a separate bedroom with a door. Might end up as a suite, but! Everyone going to bed at 7:30 sucks! Originally, the man thought I was a little nuts, but at the end of it he totally agreed that it was worth it. Try & get a balcony while you're at it - we alternated who sat with Am while she napped, & sitting looking out at the beauty was so much better on a balcony than it would've been through a window.
F) Pack the familiar lovey for sleeping, and maybe two other familiar toys, but other than that, don't worry about it too much. You can always get some nice rocks from the beach for the baby to play with :)G) Pack maybe one piece of warm sleepwear; if there's A/C your place may be colder than you expect.