Our laid back trips are easy because (1) it's just two adults and (2) we know we will be back.
However, what I would advise for planning this far out is to look at everything with your family. Get their reactions. For example, where would they like to stay? How much time would they like to be there? Once you get that sorted out, it becomes a bit easier. from there, you can determine what they would like to see. One thing I did years ago was to list every single Disney attraction, show and alternatives. Yes, it was a long list. Then I gave a list to myself, my husband and my son and we had a ranking system of basically 1 to 10 but not with numbers. Something no one wanted to do was "absolutely not!" (we had a different term) and the 10 was "yes, yes, yes!" Other terms was "with a ten minute wait" (this was before FastPasses) and "if we haven't done it yet". You can come up with your own. The lists were handed out to the three of us one afternoon and we couldn't talk to each other and then all were handed into me and I did a chart. The agreement was if two of us said "No way!", we didn't do it. If any one of us said "yes, yes, yes!", we all did it. Then we just filled in the rest as needed/wanted. This way, you can dump things your family doesn't want to do and look at what they want to do. It was eye opening for me as it made my husband and I realize my son was that into movies so The Great Movie Ride was a "yes, yes, yes!" on his list and we enjoyed watching him watching things in the attraction.