Dick, it sounds like your family is like ours. We have two older ones - 28 and 26, and the two younger ones - 19 and 16. The 17 year old who will be with us is a friend.
Our younger two miss having our older two with us on vacation terribly (as do Mom and Dad.) I can't wait until we can work it out to vacation together again sometime, but for right now, it just isn't working. At least I can say that we have bred Disney Lovers. Our 26 year old - who married a Disney Lover - went to Disney last year for her honeymoon and our 28 year old has been there the past two years with her BF - who has become a Disney Lover too. Someday we will all enjoy Disney together again - in a couple of lovely, space-filled off property condos.