Groups vs. Forums - Best Practices

How does everyone else out ther utilize thier groups and forums in BP?

I mean using the wire you can pretty much do everything in a group that you can do in a wire. Some of my users have asked me why include forums when we have groups.

I need forums due to advertising so I've told them that groups and personal wires are limited in character and retention where as forums aren't. I compared wires to twitter.

How have you used the two, and what are some best practices?