http://chessforseniors.org/ is a website showing tournaments for seniors world wide.
Thanks for posting the website. If I got money to spend, I would love to join an international seniors' tournament.
Unfortunately, it looks like that link is no longer valid. When I clicked on it, all I got was a screen that tried to sell me this domain name. Give it a try. I hope it works for you.
http://chessforseniors.org/ is a website showing tournaments for seniors world wide.