We've been to Disney twice now, so I'm far from an expert, but I do have some valuable insight to share about going to Disney with a family.
My first piece of advice would be to wait until your kids are older. 7-8 is a pretty ideal age. We went for the first time when the kids were 8 and 12 and it was really great. They are old enough to not need naps or strollers or to be carried all over. Strollers are kind of the bane of my Disney existence and the more people I can convince to wait until their kids are don't need them, the better. People use them as battering rams, they stop and block the whole walkway with them, they take up a ton of space on the buses.
This trip was even better because they are 10 and 14 and were very nearly independent. WF could be done at the pool and head back to the room by himself. MF was able to get her own food and drinks and could be told "we'll meet you outside the bathroom" and she could just go.
When you are thinking about your vacation, your best bet is the off season. Once kids go back to school, the crowds tend to be smaller. That means your kids will be missing school, but it is totally worth it. Alternately, homeschool and don't take all the single days off and group them all together into your vacation week. You can also visit Hall of Presidents, Living with the Land, Ellen's Energy Adventure and call it a school day! :)
If you HAVE to go during traditional break times, be prepared for large crowds and long waits. In the past few years, Disney has closed a few times due to capacity crowds during the holidays and summer. Considering that MK alone can hold around 100,000 people at a time, you are talking MASSIVE amounts of people, so think long and hard before you chose to go during the peak season!
You can visit WDW Prepschool (my personal favorite Disney site) or Your First Visit for crowd calendars to see what week are predicted to be lowest. Keep in mind, there really are no "off" weeks anymore. There are weeks when crowds are lower, but Disney has been offering all kinds of deals and discounts to increase attendance during traditionally slow times.
You'll need to do some research about how long you want to stay. This will depend on your family, your travel dates, and your budget. Two years ago, we went the week before Thanksgiving and if we had stayed the full amount of time we wanted, our return airfare would have more than doubled! We ended up cutting our trip short by two days and, although the savings were important, I regret that we tried to cram our full vacation into a shortened amount of time. We only had 4 park days, which included a day at Universal and we were running for 12-15 hours every single day. We were all totally exhausted and miserable by the time we came home.
This time, we had 6 parks days, no Universal and it was much better! We had time each day to take short breaks. We were able to have a couple of early evenings and a few later mornings, which made everyone so much less tired and crabby. If you can take the time, once you get over 4 days, the price per day of park tickets gets much smaller.
You'll also want to consider your budget. I figure about $1200 per person, including our airfare, but we stay and fly as cheaply as possible. You'll need to research the various resorts and the amenities your family needs. How many people are staying in a room is also a consideration because most rooms are sized for 4 and only some resorts offer family suites.
Personally, the key to a great Disney vacation is in the planning. My family makes fun of me, but I create a lovely spreadsheet for our trips, that includes all the rides, shows, characters, meals, fast passes, plus a listing of restaurants in each area that my family would eat at. 3/4 of us are pretty picky eaters, so no world showcase food or just popping in to a restaurant and finding something we'd eat for us. I need to know ahead of time which places serve food that we'll enjoy.
This is one day of my spreadsheet. On sheet one, I had the must do list. Then I had a sheet for each day with just that information. Breaking it down by day kept it from being overwhelming. Yellow is food, blue is rides, green is characters, and red is anything that had a specific time.
You'll want to start your planning at the Disney website. You can also use the My Disney Experience app on your phone or tablet. I feel like the app is better on the go, to see all of your plans in one place, while you are in the park, while the website is better for planning but your milage may vary.
I started by going through each park with the kids and asking them to list their "must-do" attractions, characters, shows, and food and I listed those things. I polled the rest of the family and was told that whatever the kids wanted was fine with them. It took us about 40 minutes to go through all 4 parks with both kids (I separated them, because they are contrary and would say that they hated something their sibling was desperate to do, just because). There was a lot of overlap, like everyone wanted to do Space Mountain, but even on the things only one person wanted, it made it on the list for everyone to do.
I know this seems like a pain and who has the time to do crap like that, but trust me. Time is at a premium in the parks and you are paying a pretty penny to be there. You will appreciate knowing what to expect ahead of time. While other people are running around like chickens with their heads cut off, you'll know when things are happening, how to get there, and you'll be able to make the most of your trip.
During the planning process, you'll also want to think about where to stay. The first question is on property or off. We stay on property. I feel like the benefits FAR outweigh any minor drawbacks. The benefits, as far as I'm concerned, are the Magical Express picking you up at the airport, access to Disney transportation to other Disney properties (including parks, other resorts, and Disney Springs), and access to the Disney dining plan.
I don't have many cons. Some people don't want to be in the "Disney bubble" their whole trip (for whatever reason) and some of the hotels are expensive. Other than a desire to just not be devoted to Disney for your whole trip, price is a major consideration for choosing a hotel.
That leads to researching the various Disney hotels and their prices. There are three main levels of resorts: value, moderate, and deluxe. Each has pros and cons and where you stay will take a lot of factors into consideration. The "value" (read cheapest) resorts also have the smallest rooms. If all you are doing is crashing there between parks, this is more than enough. Moderate resorts have somewhat bigger rooms, potentially different transportation options, and more amenities. If you are planning to spend more time in your room, the extra cost might be worth it. Deluxe is the most expensive, it offers the most amenities, the most transportation options, room sizes vary by resort. Rooms run $85-$2000+ a night, depending on the season, the hotel, and the room type.
We've only stayed at All Star Music which are pretty comparable to most low to moderate priced hotel chains (the other two All Stars, Movies and Sports are very similar, just slightly different themes). Think Holiday Inn or Comfort Inn. They have double beds, a single bathroom, and an in room refrigerator and not much else. Each resort does have a pool or two and a restaurant. The values have plain pools and food court style dining. I think that is just fine, because we aren't there to hang out at the hotel. I also prefer the food court style dining, because they have several food stations, each offering different options, so everyone can find something they like. I ate roast beef three out of the four dinners we ate at the hotel and WF had a burger every time. Other options, include salads, pizza, and snacks. Some of the other resorts offer multi room suites, hotel specific water parks, and actual sit down dining. Since we go in the off season, we pay less than $100 a night at All Stars and got to take advantage of the free dining promotion as well. For that price, I can't imagine staying off property and having to rent a car and pay for parking, as well as paying for food out of pocket, since only people who stay on site are eligible for free dining.
The other hotels in the Value category are Art of Animation and Pop Century. Depending on the time of year, they can cost nearly the same as the moderate resorts. Their theming is more elaborate and they may not be included in free dining, because of their popularity.
Part two is coming soon and will discuss more about transportation options, how to prep for your trip, and what to pack for your trip!