Another option is to bring "ready to drink" cartons of formula. Whilst ideal for the journey itself, be aware that you may not be allowed to take these cartons with you into certain countries. Sealed containers of formula do not normally present a problem.
Solid foods can be packed into a cooler, although a better idea is to bring foods with you that you can easily prepare during the journey. Avocado pears and bananas are good examples, as they can be simply peeled, mashed and served to your baby at room temperature.
Always bring your own feeding bowls and utensils when travelling with baby - many eating establishments do not have cutlery appropriate for an infant's use. A travel high chair is incredibly useful, too -- and means that you can comfortably feed your baby wherever you go. Disposable bibs, or a wipe-clean plastic bib, can be very convenient when travelling and they certainly cut down on the laundry!
If you ask for food or milk to be warmed for you, be VERY careful to check the temperature on its return. Busy waiters or cabin crew may overheat the food and you will need to wait for it to cool down. With this in mind, ask for any food or milk to be warmed well before you're actually going to need it!
Many parents worry about how to sterilise feeding equipment when travelling with baby. There are many products available to assist with this, from microwave steriliser bags to disposable bottle liners. Most stores dealing with infant feeding equipment will offer a range of travelling accessories such as these.
Other essential items for your trip will include nappies/diapers and scented diaper bags. If you're heading to a warm destination, adequate sun protection is a must! Also, consider bringing a small nightlight - if you're breastfeeding, it can be very useful in a dark, unfamiliar hotel room.
To help your baby cope with the trip and to reassure him in new surroundings, be sure to bring his favourite blanket. This can also serve as a handy "curtain" to shield an aeroplane sky cot/bassinet from the light, or for naps in his stroller when out and about.
Dress your baby in light layers when travelling -- not only does this make it easier to cope with fluctuating temperatures, but if your baby spills his food, for example, you can easily remove the top layer of clothing. Bring a change of clothes for yourself, too -- baby's mess tends to have a habit of transferring itself to his parents!
Enjoy your trip!