Hi Cynthia! This is a tough question as many families come on a strict budget and have a fabulous time then others come with wallets completely full to spend at their whim and also enjoy their vacation. I think the best thing to do is to realize what a basic vacation is going to be that includes your transportation, resort lodging, and tickets then decide from there. You can see the different pricing at
www.disneyworld.com under booking trips. Packages are a great way to go and you can add a dining plan which will give you a price that includes just about anything you will need.
Suggestions when booking a package include: add Park Hopper options to your tickets, add the regular Dining Plan not the deluxe as that tends to be too much food to try to eat every day, and make sure you sign up for the Magical Express transportation from the airport. Choosing a resort is up to your interests. The Deluxe resorts will be closest to the parks and have easier transportation while the Value resorts are less expensive but further away and more crowded. My favorite in each category are: Deluxe-Beach Club or Polynesian, Moderate-Port Orleans, Value-Art of Animation or Pop Century.
When all the major decisions are done you can think of the extras such as recreation. Add a couple of hundred dollars for things like renting boats, Pirates League/Bibbidi Bobbidi Boutique, or Disney Quest for your ten year old. And of course add some spending money for a few souvenirs.
Let the Disney site help you with your choices to get a bottom dollar amount for a nice vacation. From there let us help you plan your days and activities!