Ohio, Here We Come!!

So, we're taking our first flying vacation EVER as a family!! Nate and I are taking all four kids and we're flying to Ohio to go see my sister, Jenny, and her family. We're super-excited, but pretty nervous about the unknown. So if anyone has any advice on vacationing with kids, flying with kids, the sites to see in Ohio, or anything else, let me know. Should I pack three different backpacks, one for each flight, or pack a different backpack for each of the kids? Should I even pack backpacks or use rolling suitcases? Should I pack a diaper bag or is that a pain? Should I pack a ton of snacks...or not? Take a stroller or a baby carrier... or both? So many decisions to make. Nate thinks I'm crazy to try to plan all this kind of stuff, but I just want to be prepared so it's not stressful. So, let us know any advice you have!!