Here are some listings of parking lots. I believe the one you were remembering was the Floral Showhouse.
Niagara Falls ParkingparkingThe public transportation is now
WEGOBe sure to check the package deals for tickets - it can save you money.
Make sure to leave some time to just sit at Table Rock and watch the water pour over the edge - it's mesmerising.
Also, check out the T.W. Kriner books, In the Mad Water and Journeys to the Brink of Doom. They tell of all the people (and animals) who have gone over the falls over the years.