Topic idea for daily contest could be: best quote you heard that changed your life, what you value most, what you love about your partner, would you choose your partner again if there's a next life etc. While for weekly contest could be; 150 words short story, sharing phylosophy about life love and marriage, best fun moment you have for each week, highlight your week in 50 words, riddles and their meaning, etc.
Just something that will be spontaneous and interesting. The photo contests are already to many . So just do something different