Packing: ‘Do We Really Need All This Stuff?’ : You can lighten up by buying or renting a car seat and other incidentals en route.

“Are we going to Antarctica or to Florida?” my husband complained as we staggered through Chicago’s O’Hare International Airport with three kids, two backpacks, one car seat, one stroller, an overstuffed diaper bag and a heavy duffel. And those were just the carry-ons.

“Do we really need all this stuff?” my son asked, surveying the pile tumbling out of the security X-ray machine.

I thought I was being prepared but maybe I was a little overzealous. And even with all of my careful planning, I ended up buying the baby a $25 sweat shirt in a pricey O’Hare gift shop because she got carsick on the way to the airport and ruined her only warm jacket. Everything else in our luggage was short-sleeved and planes are always cold, I muttered as I frantically searched airport gift shops for a tiny sweat shirt that didn’t cost $25. (There weren’t any.) So if you’ve got a toddler, make sure you pack a complete change of clothes in readily-accessible baggage--extra sweat shirt and all.

Could we have managed without some of the other stuff? Maybe fewer toys and snacks would have lightened our load. There are thousands of toy stores across the country, not to mention supermarkets and drug stores where you can buy everything from formula to diapers to an umbrella stroller for $19.99. But I figured that with my luck, all necessary stores would be closed when I desperately needed children’s Tylenol or something to satisfy my starving kids.

This is not to say that you need to drag the entire nursery along. Older kids do not require as much equipment as babies. And particularly when traveling domestically, you can pretty much rent whatever equipment you need--whether it’s a crib, a highchair or even an extra bed or playpen. Just call your local rental store to get the name of a rental establishment near your destination, or check the Yellow Pages or directory assistance at your destination under “rentals,” advised Ralph Wenzel, an official of the American Rental Assn. Rental prices aren’t bad, either: a crib will probably cost about $22 a week. But if you’re traveling during the summer or holidays, Wenzel warns, reserve the rental equipment as soon as you make plans.

Or perhaps you’ll get lucky and the hotel at which you are staying will be equipped with a crib. Many are. Even cruise ships have high chairs and cribs. But make sure to ask when you book reservations--especially if it’s a busy season. Whether there is a charge for such equipment varies widely from hotel to hotel.

If you want to hedge your bets and you travel frequently, portable cribs (at roughly $79.95) have proven to be a good investment for some. That way you know that wherever you stop, your baby can sleep safely and comfortably.

Even if a crib is available at your destination, there will still be a number of things you want to drag along: special toys, favorite videos (particularly if you’re going to be staying at someone’s home) and definitely a stroller. I don’t mean a big, clunky baby buggy that weighs a ton. I mean a cheap umbrella model that you can throw into a plane’s overhead bin or into a car trunk. It will save untold hours of whining--even if you have a 5-year-old. Kids get tired of walking, particularly in airports and cities.

Another piece of equipment that is easy to pack is a portable umbrella. If your vacation will involve heading to the beach with a baby, it is smart to take an umbrella to protect him from extended sun exposure.

If you don’t know whether the restaurants you’ll be visiting at your destination have highchairs, you might want to invest in a collapsible booster seat (about $30). Toddlers not only will be more comfortable, they won’t be able to escape as easily.

While those who travel to Europe with their kids say they can find everything they need, from diapers to formula to sunscreen, it would be wise to check ahead with the tourist board of the country to be visited and keep in mind that you are most likely to find what you need in large cities.

To keep baby bottles cold, pick up one of the soft, insulated bags and pack it with frozen blue ice. To ensure that the bottles stay very cold, stick an ice cube or two in each.

And don’t forget resealable plastic bags can be used for anything from dirty clothes, to trash to diapers. Sticking a wet washcloth in one of those bags is always a good bet for cleanups.

Lugging the car seat through an airport can really slow you down and they can easily be rented with a car for a few dollars a day. (Charges vary from $3 and up. Check when you book the car rental.) But I think they are worth the effort. Airline spokesmen acknowledge that a young child is safer on an airplane in a car seat approved for use on an aircraft (a sticker on the bottom of the seat should say if it is FAA-approved) than on a parent’s lap.

And there is a rub: Even if you have the right kind of car seat--and most standard models meet FAA approval--to guarantee that you may use one on board, you must pay for an airline seat for your child. It is, however, general airline policy to give you an empty seat for your baby--and car seat--if there is one available, airline spokesmen say, but you should make a special request for this at the gate or when you check luggage. An available empty seat may not be offered without your requesting it.

And be forewarned that you may meet with resistance at the gate. When I recently arrived at an airport with my three kids and car seat in tow, the agents shook their heads, said the flight was full and insisted I check the car seat if I wanted it to arrive when I did. But when we boarded, we found that there were plenty of empty seats. By then, though, it was too late to retrieve the seat. Next time, I will wait longer to board, hanging on to the car seat until the very last. We had better luck with it on another flight. And it was well worth the effort. At the very least, I was more comfortable. And so was my 1-year-old Melanie. Safer, too.

That didn’t keep her from throwing up again on the plane, of course. Luckily, I had wet washcloths in a plastic bag and a good collection of paper towels.

Just remember, when taking the kids, traveling light is an oxymoron.