You give thought when you pack suitcases and duffel bags for plane or car travel; but do you give the same thought to your all important carry on bag? Do you pack a carry on bag even if you're traveling by car? I do, and consider it a must for pleasant, organized, and efficient travel. What will you need at finger tips? How heavy will it be (more important if you're packing for a carry on for plane travel), will it go through security safely?
The items I put in my carry bag regardless of whether I'm traveling by car or traveling by plane are:
A water bottle
If I'm traveling by plane I add a pair of footies, and sometimes a book.
I have lots of canvas bags and use them constantly; but for carry on they must have a zipper and an extra pocket. The extra pocket is where I put my boarding pass, and my footies. I like the little footies for standing and walking through the security line. Not about to walk on that floor or carpet where thousands of people have; many with dirty feet. Boarding pass is something you want to be able to grab quickly, and not have to root in backpack, purse, or brief case/ laptop case for.
Pack LIGHT! I put my yarn, the needles or hooks I need for that item, and pattern if I'm using one in a zip lock bag sealed inside the carry on. Keeps it neat, clean, organized, and dry. Water bottles can leak, and have condensation which can be a problem. Likewise my GPS and or book would be in a sealed zip lock bag. I always use the freezer zip locks, as they're heavier and hold up far better than the regular ones. Additionally, if security needs to look through your carry on, they don't make a mess of everything. They can see right away what everything is.
I always have the camera in a small padded camera bag for protection again inside the carry on. Ladies this is for you, leave enough room in your carry on bag to put your purse inside it and still be able to zip it shut. The carry on bag should have shoulder straps so you can comfortable carry it. The bag needs to small enough to shove under the seat in front of you. If you count on being able to put it in the above compartments, it's not then at your finger tips. It's not convenient and you have to jump and down constantly to get what you need. Not only is that a nuisance to you, but it's a HUGE annoyance to your fellow travelers, and sometimes it's not possible. Sometimes with rough air travel you're not permitted to get up; and sometimes due to people carrying on too much your carry bag is no where near you. Again, that defeats the purpose. PARENTS should pay particular attention to this. You probably need items for your children, you need it to be organized, you need it to be at finger tips.
Can you count the number of times you've seen a harried traveler not being able to find something they need? The mother with a huge heavy purse flapping open as she bangs her way down the aisle. People who need help lifting their carry on bag because it's too heavy for them to lift. Bags that end up needing to be checked because their too big, they don't fit under the seat and the room above is gone? People with multiple plastic bags losing items as they go? Take time, think about what you need and pack it neatly. When you throw something together, you risk breaking it, losing it, and causing travel delays.
Always toss in a couple of extra zip lock bags in your carry on bag, and your suitcase. They are always useable.