"Kate has had time to get used to this and these last eight years have been about falling in love with Prince William, getting to know him, getting to know what it's going to be like to be married to the future king," Nicholl said.
At 29, Middleton is older, confident and has the support of not just Prince William but of her new in-laws. She understands the expectations of a princess. Perhaps Middleton will have less rigorous demands initially than Princess Diana, which should allow her even more time to settle into her new role.
"I think she will find the transition far more relaxed than it was for Diana because the expectation on her will not be as great," Morton said. "William will be working as a helicopter pilot and will not be doing full-time royal engagements so they will be able to dip in and out of the public arena, in a way that Diana was never able to do."
Middleton will come under tremendous pressure becoming the newest member of the royal family but, this time around, royal watchers say, the princess will be in a better position to handle all that comes her way.
"The royal family are a tough outfit and Kate will have the ghost of Diana to contend with," Morton said. "At some point -- it won't be this year and it won't be next year -- but in the future, she will define herself, as her own royal, in her own way."
For more on the lessons Middleton has learning from Princess Diana, tune in to a Barbara Walters special, "The Royal Wedding: A Modern Fairy Tale," April 18 at 10 p.m. ET.