A.C.
We usually try our best not to carry on too much. Pack a small bag with some snacks, diapers, clothes, new toys (target has a section with small toys great for travel), a book or magazine for the adults. You may also want to bring a portable DVD player and some headphones. That always saved us on a long flight.
If you're just worried about getting all your luggage to the check-in counter, which was always a problem for us, have your husband drop you and your daugter and all the luggage at the curb. He can go park the car by himself and get on the shuttle to the curb w/out all the lugging. Then get one of those carts and push everything to the counter. Check everything...you'll be glad not to have to carry all sorts of stuff through the airport.
If you are using the carseat on the plane, then after check-in you would just have the seat and the one carry-on and your purse.
We always borrowed a strap from a duffle bag and hooked that around the car booster and carried it on our backs. Simple and easy and we didn't have to purchase an accessory that we'd rarely use.
Have a great trip!!