They cast wives over a decade younger than Bill & Ted
So Keanu is born 2 September 1964
Alex Winter is born July 17, 1965
Princess Joanna
1st - Diane Franklin - February 11, 1962
2nd - Sarah Trigger - June 12, 1968
3rd - Jayma Suzette Mays -July 16, 1979
Princess Elizabeth
1st - Kimberley Kates - 15 August 1969
2nd - Annette Azcuy - age not listed
3rd - Erinn Hayes - 25 May 1976
So as you can see, they have recast the princesses every movie.
But for characters who are meant to be around the same age, I think the age gaps are a little much.
Like 17 years between the first princess Joanna and the new one? Big gap!