I can help with the Atlanta Waldo information. Oakland Cemetery is where the family of Albigence Lamar Waldo is buried, just outside the cemetery office. He married Anna May Slaton, sister of Gov. John Marshall Slaton. Gov. Slaton and his wife, Sarah Frances Grant, are buried at Oakland in Grant's Masoleum with her parents. (So when someone asks you who is buried in Grant's tomb, the answer is Gov. Slaton.)
Most Waldos in the U.S. descend from immigrant Cornelius Waldo who came to Ipswich, Massachusetts before 1647. Albigence Lamar Waldo's Waldo line is Cornelius > Daniel > Zachariah > Joseph Warren > Benjamin > Albigence Lamar.
Albigence Lamar Waldo is named for Dr. Albigence Waldo, who was an Army surgeon under Gen. George Washington during the American Revolution. He maintained a diary which included the terrible winter at Valley Forge. His descriptions of the conditions there are well known, and the diary has been published.
There is no close connection, if any, between Albigence Lamar Waldo and your grandfather, Arthur Waldo. Albigence's grandfather came from Pomfret, Connecticut, to Newberry, South Carolina, about 1800. Albigence's father moved from South Carolina to Florida about 1847 (first Madison County, later Ocala, Marion County). Albigence, as a young man, moved to Atlanta, Georgia, about 1874.
Perhaps others can help you with Arthur Waldo but some more information from you, like dates, spouse's and children's full names would help them help you.