If you are flying in for the wedding you have a few options.
A. Fly into Toronto, and train/bus/drive to Kingston. (TO is a 4 hour drive from Kingston.)
B. Fly into Ottawa, and train/bus/drive to Kingston. (Ottawa is a 2.5 hour drive from Kingston.)
C. Fly into Toronto/Ottawa and then fly into Kingston. (Kingston has a very small airport that does have commuter flights from both Toronto and Ottawa.
Go to http://www.theflightnetwork.com for really great deals on flights!
