This is a big question when planning your trip to Walt Disney World. To insure that you don't buy too many or too few tickets into the theme park, and you get exactly the experience you want, you need to plan.
First step is to sit down with a calendar and ask yourself, "How many days will we be on vacation?". After this is determined, ask yourself the following:
Do you plan on going into the theme parks on your travel days, the days you arrive and depart?
Do you want to go to the theme parks every day or do you want to a day to just relax at the resort or explore Downtown Disney?
Once you have decided the number of days you need, you now need to decide what kind of experience you want to have. So ask yourself the following:
Do we want to stay at one park all day or have the option to "park hop" so you can go to any park at any time during that day? If you want the option to "park hop", you will want to add the Park Hopper option onto your tickets.
Do you plan on spending any time at the water parks or Disney Quest? If so you, you may want to consider adding the Water Park and More option onto your tickets.
And finally, the last question you ask yourself is, "Do you plan on returning to Walt Disney and think you many not use all the tickets you purchased?" If you think this might be an option, you will want to add the "No Expiration" option onto your tickets.
These tickets are called Magic Your Way tickets because you choosing the tickets that are best for you and your family. For my husband and I when we travel to Walt Disney World, we always choose the Park Hopper option. We opt to decline the no expiration option because we plan our trip in such detail that we know which days we will be where, so we get only the number of tickets we need. We also opt to decline the Water Park and more option. If we choose to go to a water park during our visit, then we just pay the daily ticket price for the water park.