In addition, while they may not have memories of the trip in their adult life, from 3 to 5 they can remember much of what they did when 2-3, and this forms and shapes their experiences during these later years, that will in turn become their first life memories.
As well, with advances in photography, they will forever be able to see--even without remembering-- just how much they were loved.
We are strong proponents of whole-family travel, and have a 3-week cruise planned with our 7, 5, 3 and 1 year olds next year. It's part of our tradition to take a trip every time we have a newborn. They love it... and we love it!