In time for wedding season, Ancestry has launched Niagara Falls, Ontario, Canada, Honeymoon and Visitor Registries, 1949-2011. The index for this collection is available for free, without subscription. The scanned images, however, will remain behind the paywall.
This somewhat unusual collection is from the Niagara Falls Tourism Office, and it contains 680,114 records. You can search by name, location, marriage date, and keyword or browse. 
Niagara Falls first received its reputation as the Honeymoon Capital of the World in 1801.
Today, about 50,000 newly wed couples visit Niagara Falls each year. Many choose to sign their names in register books kept by the Niagara Falls Tourism Office, which have been digitized and indexed for this collection. While the majority of registers in this collection contain names of couples on their honeymoon and their marriage dates, some contain records of other visitors to the tourism office.
While it appears that not one of my family members ever signed the register, I did notice some entries in the register include a home address.
The index was keyed by volunteers involved in the Ancestry World Archives Project.
You can start searching the collection here.
Are there records for the years previously. I believe my grandparents went to Niagara Falls in 1919 for their honeymoon.
Good question. I suspect they may not be available, otherwise they would likely have been indexed before or at the same time as the recent collection. I suggest you send an email to the Niagara Falls Tourism Office.