Quickly I found that several Toronto museums also offer children's activities and projects for Family Day in Ontario, which also falls around this time. Bingo, there's another article to write!
I took notes for each holiday, and soon wrote a pair of articles.
"Two Toronto Museums for Valentines Day 2015" covers the one topic. Actually, they happen to offer somewhat similar approaches. You may be surprised at what they have in common.
"Enjoy the 2015 Ontario Family Day in 6 Toronto Museums" covers the other topic. Obviously it's more popular with museums in Toronto.
One Writing Tip from Twin Articles
I didn't start with the idea of researching several related topics at once. The material I found just forced itself on me.
You can be smarter about it. Plan ahead, pick some related topics that you can research from a few places. Split up the information, then write each article.