Since you aren't going to have time to do it all you're going to need to prioritize. Spend some time at the Walt Disney World website or the My Disney Experience app and decide what things are “must dos,” what are “nice to dos” and what things you're ok with skipping entirely. Plan what park(s) you'll visit based on these lists. Be sure to research if a ride will work for everyone in your group, for example making sure all kids are tall enough to ride. You don't want to waste time or a FastPass on a ride you can't do!