I enjoy 
www.forums.parenthood.com  which is a site I used to work at and helped rebuild several years ago.
I am a recent member of 
www.eons.com which is for people 50 and older.
I love getting ideas for my house and gardening at 
www.gardenweb.com which I go to only sporadically. 
I spend more time here than at any of them, but have been part of parenthood.com the longest by far.