I sat in traffic yesterday, on a Sunday afternoon, for one hour, along with about 10-15000 other people on 285 between Ashford Dunwoody and Chamblee Dunwoody. There was a tractor trailer wreck that blocked all lanes eastbound.
This is too common on 285, and that's why I avoid it most of the time.
I like surface streets for crosstown commutes and most of time I take Clairmont off of Peachtree to downtown Decatur. That's a 15 minute ride on a good day. Traffic bogs down at Century Center and through to Briarcliff, but loaded tractor trailers don't jackknife on Clairmont very often. At worst, it's a 30 minute drive.
And, in order to get to Clairmont, you need to take Ashford Dunwoody south, inside 285 to the Johnson Ferry intersection, then follow Johnson Ferry to Peachtree, then left on Peachtree then right on Clairmont. On a good day, that takes 10 minutes.
At worst, it's a 30 minute ride from Perimeter Mall to Peachtree.
And even at it's worst, I prefer the north-south surface street commute over 285 ...