I can't stress enough how cool MagicBands are. As soon as I checked into Disney's Port Orleans Resort (Riverside) I received a MagicBand (free if you're staying at a Disney resort) that I used as my hotel room key, to pay for everything at the hotel and parks (you enter in your credit card info along with a pin at check-in), to get into the parks, and for FastPass+ reservations. It made the whole experience seamless — you don't have to keep track of your hotel key, credit card, fast passes, or paper park passes because everything is contained in one wrist band.
To take advantage of the MagicBands you just need to download the My Disney Experience app where you create an account that links all your Disney hotel and park pass info and can make all your FastPass+ reservations months ahead of your trip. It also includes an in-depth map and wait times for rides.