It depends on what you would like to do once you are there and what type of budget you can work with. Without knowing what package you have purchased (if any) or where you are staying....
Food:
If you plan to eat in the parks, menus are available online (with prices)
it's just a matter of figuring out what types of food you would like. If you don't know restuarant names, feel free to ask because most people here can name them all in their sleep!:slurp:
If you want to eat counter service (hamburgers, ect.), figure on $15-$20 per meal depending on what/how much you guys eat.
Drinks:
If you both plan to drink alcoholic beverages, figure on a minimum of $5 a drink.
Entertainment:
Not all entertainment is in the parks. Disney offers many other activities, some free, some not. You can choose from golf, miniature golf, horsebackriding, boating, fishing, movie theatres, surfing lessons, spas, swimming, and tennis. (*swimming and tennis are free)
They also offer various park tours (scuba, dolphins, segway, gardens, safari,ect.) These are all priced differently (*+/- $70, some higher some lower)
Cirque Du Soliel (about $75 +/- depending on seating)
If you have an Ultimate park pass (all Disney magic packages do) then you get admission into Disney Quest otherwise it's a little over $30 per person.
I hope this gives you a better idea of what you will need to bring. Have a great trip!!!