How was marriage used in diplomacy and power politics by the very rich? At http:englishhistory.nettudormonarchscleves.html there is a nice short history of Henry VIII's marriage to Anne of Cleves. At the National Portrait Gallery www.npg.org.uk you can search for the portraits of Anne which allegedly misled Henry about her attractiveness.
Statistics are often underused in history, despite being a valuable source of information. The Office for National Statistics www.statistics.gov.uk
can usually turn up materials on most aspects of social life. Students looking at the 20th century can investigate statistics on marriage, crime, education, poverty and see how much the century changed.
A difficult but interesting area of study is the way societies often misconceive the way earlier societies thought. Find examples of the way 19th and 20th century values and ideals (halcyon days) have been projected backwards and produced a distorted view of the past.