Hi Dana! Planning your first Disney vacation can be a bit daunting as there is so many things to consider and so many things to do while you are there. The first thing you must realize is that you likely cannot do it all so pick and choose what is important for your family.
There are four theme parks at Walt Disney World and most guests want to visit each one during their stay. You can start by choosing a four day
Park Ticket to see how it fits into your budget. I suggest you add the Park Hopper option but it will add to the cost. This allows you to go from one park to another on the same day. If you do not get the hopper option then you are restricted to only one park each day. You can come and go but only to that one park.
If you can plan some time at
Disney Springs which is a large area of great dining and entertainment and also super shopping! Time at your resort is also a must for the family to enjoy the pool and facilities.
In review I would not get less then four day park tickets and would add the hopper plan to it. That way you can head over to a park during the day and then to another that evening to watch fireworks. Each of the four theme parks offer great adventure for all ages young and old. Plan at least an afternoon at the resort pool, and if you can at least a half day for Disney Springs. Since this is your first trip I would not worry about going to the water parks. There is so much to do and a water park could certainly be added on the next visit.
Let us help you with all your planning questions. We don't want you to stress over this but instead have fun.