Diapers: I packed 6 per day, plus 1 diaper for every hour of flight. Even though I didn't think I'd change every hour on the plane, it makes me feel better to have a large reserve in case of delays (either in the airport or stuck on the plane). Especially since I have never seen diapers for sale at the airport and I hear about people stuck on planes for hours. Diapers in other countries, even the same brand, may have a different texture. I also didn't want to risk running out. I ended up with 10-15 extra for a 3 week trip. Plus one package of swim diapers and two swimsuits. Wipes: we use them for diapers and food clean up. Packed 3, plus 1 in diaper bag. I ran out after 2 1/2 weeks and had to buy more 2 more packs. We didn't finish the last pack. Diaper disposal: we toss the wet ones as is, and bag the dirty ones. Both just go in a wastebasket at hotels.
Things I found useful
In transit:
• Toys packed in separate bags divided for time and rotated. So, for a 4 hr flight, 1 bag for the first half, etc. This keeps the toys interesting and you won't end up with tons of toys all over the place.
• Also get some new toys and reserve their introduction until needed.
• Overseas flights: you have to make sure you get a bulkhead seat with access to a bassinet. You may have to pay extra for this and arrange it far in advance. Even doing that, be vigilant when checking in, since they sometimes switch seats and might not be helpful. We had lots of trouble with seat assignments--ground staff would say that we had the right assignments or that they had to do it at the gate. The gate people would say that they couldn't do anything and the flight attendants would have to help. The flight attendants would say that we should have done it with our travel agent. More than once, we had a battle with flight attendants. So, the bassinet seats are 1 aisle + 1 center (or window). Don't leave the ticket area until you are certain they have done it. You don't want to end up stuck with a baby on your lap for 10 hours. The bassinet is small and the sides are shallow (I would say not good for much over 1 yr). The airline may not provide food for bassinet babies so you need to bring all the food for the duration of the flight. Had we known how small the bassinet was, we would have bought a seat. At 19 mos, he was trying to stand in it (the sides are maybe 10 inches).
• Bring food in a large ziploc with everything you need in it (bib, wipes, spoons).
• domestic flights allow you to bring juice for baby, but not water. Just say it is juice going through security so that you don't have to empty the sippy cup and then refill it before getting on the plane.
• Shawl--I use those ruanna style shawls a lot. In addition to being warm and thin (easy to fold and put away), they are excellent nursing cover. And double as a comforting baby blanket since it smells like mommy.
Once there:
• An extra blanket & changing supplies to create a changing table in your room. I found it was nice not to have to use the diaper bag supplies in the hotel room.
• Reliable snacks for baby (apple sauce, org raisins, cheese crackers....) anything she is used to eating in case she doesn't like the food there
• pack a first aid kit with alcohol wipes, thermometer, bandaids, neosporin, baby tylenol
• ipod & speakers to make different places feel like home (especially if you normally play music for bedtime)
• a couple of bath toys and small bottles of normal bath goo.
• In the hotel room, I designate an area for toys (a low shelf) and show him where they are so that he can find them.
• 2-3 sippy cups: one for room, one for diaper bag, one to lose. (maybe bring some dishsoap)
• In addition to a stroller (mia moda makes a great light stroller excellent for travel), bring a sling. Eventually they need to be held and then you are pushing the stroller and trying to carry them. I like hot slings b/c they fold and are machine wash as well as pretty comfortable. http://www.hotslings.com/
That's all I can think of for now. Preparation seems to be the key to stress free travel for me. Good luck.