Nantucket Bag from Overland Equipment. This has to be one of the best--if not the best--personal item bag I've ever seen.
Right off the bat, this bag has a pass-through sleeve that slips over your carry on suitcase---not super common and extremely handy. You don't even see it when just carrying the bag, it's totally concealed and just looks like a regular tote. This makes the perfect match for your carry on, just slip it on and off as needed, no fumbling around at the airport. It stays secure on your wheelie and your hands and arms are free and comfortable. When you're on the plane, you'll have everything you need.
Inside the bag is the perfect amount of organization with pockets for sunglasses and electronics, and some padding for your laptop and/or tablet. It has a zipper closure, so it keeps all your stuff secure--I'm surprised how many totes like this do not have a zipper feature and it's important. There's a slip pocket on the front perfect for your cell phone so there's no fumbling around when you hear it ring.
You can fit a ton of stuff in this bag--a laptop, tablet, small blanket, food, and more, I can't imagine needing anything bigger for your personal item. Finally, the black is sleek and low profile, something I love in travel gear, though it does come in other colors. You could also use the Nantucket as a tote for school, work, or the beach, it's a very versatile bag. Find it HERE.