We have done both surprises and included them in the planning. We've surprised them a couple of weeks out from a trip, or at the airport in Austin on our way to Disney World ("what do you mean we aren't going to a family reunion?"

). I totally agree that including an older child in the planning can be fun. Especially if they've been a few times. Including younger kids usually isn't productive (ie Me: "What would you like to do?" My 5 year old: "I want to ride Dumbo"

) and they really don't have a sense of time on that far of a scale especially. 16 months is the same as 16 years or 16 days,