I've been meaning to reply to this thread for a week now, but my wife and I were on an epic road trip and just returned last night.
I consider us expert Disney planning people....not trying to brag, but we've been going for 30 years. A lot has changed, especially recently.
I'll keep this high level, but Disney World can be an excellent family vacation, but there are several things you need to be aware of, first.
1. Planning - unfortunately today, DisneyWorld requires a TON of advance planning. Which park on which day (we go by the longest hours for any one park to determine which one we will be visiting on which day.)
2. Are you planning to Park Hop (jump from one park to the next? This can be useful, if you visit the Magic Kingdom for early entry days, but then want to finish in Epcot especially if you want to have dinner in one of the lands).
3. Time of year - yes, there are lesser crowds during certain times, but you especially want to avoid the heat & humidity. Jan - Feb are very good, but the parks close earlier so it's a trade off. November is good, especially if you would pull your kids out of school before the Thanksgiving breaks start....so too is early December.
4. Remember when I mentioned planning? DisneyWorld requires advanced dining reservations, 6 months in advance. If you don't have them, you'll be frustrated when you can't just show up, sit down and have a meal.
5. You need to use the Disney Genie and Disney Genie + service in order to avoid long lines for the most popular attractions. This is unfortunate, because not only is this an extra cost - it also means you can't just be spontaneous. Also, you have to plan to wake up every day before 7 a.m. in order to book the most popular rides, like Rise of the Resistance, etc. This kind of takes the luster off a relaxing vacation idea, but no one said DisneyWorld is relaxing.
6. In order to do all the Parks and surrounding areas, you need a minimum of 6 days - more if you want a more leisure pace.
7. I do recommend to stay on property (a Disney hotel) because the transportation system is good - and there are several price tiers to accommodate your budget.
8. Yes, Disney is expensive....but if you compare a price per day vs a weeklong stay in Vail, including ski passes, you get a lot more. So it's all relative.
9. Lines - again, with a lot of planning, you can avoid most of the long lines, but you will have to queue up for a lot of rides. It's all part of the experience, but it isn't 75% of your day, either.
10. There are a lot of experiences besides the rides, like shows, character breakfasts etc. that also add to the experience and you aren't waiting in a line!
11. Visit Disney specific forums for the latest news such as ride closures, special events, etc.
This is a very general list - but if it seems overwhelming just to take a vacation, consider using a Disney Planner that specializes in structuring your ideal stay. Also, sign up for this newsletter:
www.mousesavers.com - each month it provides a lot of valuable data and savings.
Good luck!