1.   I miss the farm, but I could go on for hours about how horrible it was, how brutal it was.

2.   Nancy would rattle on for hours about her grandchildren.

3.   We talked for about an hour about his new makeup line.

4.   We talked for hours about the good old days.

5.   I had to listen to Tony rabbiting on for hours about his work.

6.   He tends to stand around and beef for hours about any slight, real or imagined.

7.   A science-fiction maven who could talk for hours about fictional technology.

8.   He harangued us for hours about the evils of popular culture.

9.   He can talk for hours about banking, collegiate music, gardening...