I haven't read thru all the threads..But the right age is when you decide it is.For us that age was 4 yrs old, but that was because 1) my DD is an only so there was no other age groups to consider 2) we did not want to deal with diapers and strollers and 3) we wanted her to get the most out of the trip.We had a blast and do not regret waiting till age 4 at all