For Princess Kate, 32, and Prince William, 31, the decision came down to the balance between royal duty and parenthood to their son, Prince George.
The choice to undertake the extensive journey to Australia and New Zealand, where the royal parents touched down with George Monday for a three-week tour, "is entirely their own," William's private secretary, Miguel Head, tells PEOPLE in this week's cover story.
Whether at home in England or on her first journey Down Under, Kate structures her life in a way that allows her to toggle between her royal duties and motherhood.
"When she works in the evening, she spends the preceding day with George," says a royal insider.
The princess also carves out time for romance with her husband of nearly three years. The couple is expected to spend two nights away from George while he remains in the care of new nanny Maria Teresa Turrion Borrallo.
"It's not the future king and wife who will do as she's told," says a friend of the couple, "but a husband and wife in the modern world."
Reporting by SIMON PERRY
For much more on this story, including a closer look at Kate's entourage and her travel style, pick up this week's issue of PEOPLE Magazine