I think it will be beneficial to go out and browse the disney guides that are available in your nearby bookstore and purchase the one you feel you are most comfortable with.
The guide will help you to become familiar with the basic ins and outs of the wdw complex while giving you ideas about what rides, shows, or attractions are 'must sees' for you/your family. It will also help you to price the cost of park tickets, meals, snacks, and souvenirs so you can devise some kind of a money budget (if you so desire).
Also, I would add to thoroughly research the particular hotel you would like to stay at no matter if its' on property or offsite. That way, you will know exactly what each place has to offer in terms of amenities such as swimming pools, laundry areas, restaurants, in room refridgerators, etc. or whatever else is important to you.
I would suggest to come up with at least a 'rough itenirary' for touring the parks so you'll have a general plan for what you will be doing from one day to the next; but also allow for some 'leeway' and 'gaps' along the way so you won't feel rushed.
For example, be sure and leave some time open for just doing whatever you feel like at the spur of the moment along with allowing some downtime by just relaxing around the hotel, taking a swim in the pool, or even sleeping in late one morning.
If your kids are really big fans of the characters, it would be great to pick up some autograph books so they can get their signed autographs. Also, bring along camera and film so you can take pictures if you want; or even a camcorder.
In addition, if you or members of the family are especially 'sensitive' to heat and humidity; I would pass along that the summer months are definitely without a doubt hot at Disney (we have always gone during summer in August but have grown accustomed to the heat over time). During this time temps are in the 90s everyday with a sprinkle of showers occurring periodically.
So, if you are not at all a fan of 'daily' hot weather and are easily irritated by constant heat of the sun, a spring or fall visit may suit you best rather than summer.
I hope you enjoy your visit to Disney.
