Let KAYAK do the searching
Based on KAYAK hotel searches, the most popular destination is Toronto (94% of total searches to Lake Ontario). The next most popular destinations are Mississauga (3%) and Hamilton (2%). Searches for hotels in Niagara-on-the-Lake (2%) are also popular.
KAYAK users have found double rooms in Lake Ontario for as cheap as €30 (Toronto) in the last 3 days. The average price is €299.