The Little House by Virginia Lee Burton takes place over a century or so, with the great-great-granddaughter of the builder moving to house out to the country. Many books with longer time frames than the common day or week are capped at a year, encompassing the cycle of seasons. The Little House feels timeless by starting with the cycle of seasons, losing it in the city and returning to that familiar cycle by the end.
From Recess: http://www.recess.ufl.edu/transcripts/2006/0202.shtml
"Although this may seem a statement on the unhappy results of unchecked urban growth and the blessedness of the rural life, Burton claimed her primary goal in writing this book was to convey the idea of historical perspective and the passage of time in terms a young reader could understand."
I'm not sure she succeeded in her goal of showing the passage of time to most young readers, but she certainly created a great work that will stand the test of time.