Have you considered attending a church? Before you get annoyed and say you're not religious, there are churches for that, too.
I am an atheist who had some exposure to Unitarian Universalism as a child. In college I went a bit more, and then after moving to Seattle, I found the local congregation here. It's basically what I call the "believe what you want to believe" church. It focuses more on the inherent dignity and worth of everyone, regardless of beliefs, and is a very welcoming community. Ours in particular has what we call "covenant groups" where you get together in small groups and have discussions. I was part of our "young adult" group (age up to 35) and made some timeless friendships. One friend from there, I ended up being her bridesmaid and she ended up marrying a mutual friend we both also met there. The sense of community I got from the church is rivaled only by parent discussion groups I've been in and the close-knit dorm I lived in in college.
I also second meetup.com. And if you hike with the kids, I've heard good things about Hike it, Baby!