There are some good deals out of Toronto and Montreal…
Toronto YYZ – Nice NCE on Turkish Airlines for $517USD
This fare is available late March and all of April. You have to have a long layover in Istanbul, however, you may qualify for a free hotel in Istanbul from Turkish Airlines. From what I’ve heard they’re nice hotels, and Istanbul is a GREAT city to have a full day in!
Search the fare on ITA Matrix and Kayak.com.
Montreal YUL – Rest of France ~$515USD
Similar to the above fare, but available to the rest of major French cities, including: Nice NCE, Bordeaux BOD, Toulouse TLS, Lyon LYS, and Marseille MRS.