I don't think there's a "right" way. Every child is different.
I know that the church hopes that families will sit together unless a child is disturbing, and then then families deal with it the best way they can.
Again, that depends on the family and the way they've chosen to handle it.
I have a really hard time with our "mothers lounge" for the reason that families are to sit together. I know that the church take-out many of the cry rooms because they wanted children to learn to sit with their family. For us, letting our kids walk the halls just seemed to be a reward for being disturbing. That was our reasoning (and frankly, more mine then Drew's -- I knew if he left SS -- he'd go out in the halls and be gone most of the rest of the class).
Again, that's just me. :)
*It's my blog and I'll give my opinions if I want to...... :)*