I'm facing a family trip in Dec. 2018 and we will have challenges trying to make everyone happy. There will be 4 generations on that trip. Fortunately, we will all stay at the same resort. Also, the dates of the trip is not a big factor. We have agreed on this part so far. We are going to choose dates based on free dining opportunities; we love that promo. There are other promotions and it may help to go at a time when you can get a deal.
Anyway, I have realized breaking up at times may be the only solution. Besides different likes and dislikes you may find some are early risers and some are not. The same is true with late nights. Some will be okay with being out late and others will not.
We will absolutely have meals all together. But even that can be a challenge. We have a vegetarian in the group, for example. We will probably do more buffet restaurants just to make it easier and hopefully there will be something to everyone's liking.
It may take some discussions to figure out how much you can be together for rides and shows. I would strongly suggest to try and be in agreement on your first, three fastpasses each day; so, you can at least be together for a few rides. Then, everyone can book their fourth fastpass and so on together or not. I think it's best to get the first three fastpasses done early. That will give you more opportunity for additional fastpasses. Pick core hours that everyone can agree to being at the park together early. This may not be rope drop or early extra magic mornings. Then, use your first, three fastpasses during those core hours.
I find it particularly hard to guide someone who has never been to Disney World. Try to provide some links; so, they can get a better understanding of it all. Provide some links for u-tube videos for rides and shows. Get the Disney World vacation DVD.
Also, I have come to realize it's harder to take a group trip. Everyone will need to compromise some to make it work.
Keep in mind everyone's pocketbook may not be the same for the trip. Make sure everyone realizes the cost of the trip especially the newbies. If you want to do extras like backstage tours or dessert parties and such make sure everyone can afford it. This includes any night time club entertainment. Alcoholic drinks are quite expensive at Disney.
If you prepare and plan properly it can be great fun going with others.