I was at SFGAdv on July 12th (a Thursday) and really didn't have a big isue with crowds. Two things really influenced this though...I went to Rise and Scream an hour before the park opened, and Kingda Ka was closed. In the first hour and a half, I was able to get on El Toro five times, and Medusa, Runaway Mine Train, both sides of Rolling Thunder then hop on the sky buckets to get me over towards Skull Mountain. Had I showed up at the normal entry time, I'd have had to wait in line for all of those rides (I did the El Toro and Medusa rides during Rise and Scream, then immediately after did Rolling Thunder then Mine Train).
The rest of the park wasn't even that crowded, with the only significan't waits being 45 minutes for Nitro and 30 minutes for Superman. Everything else was under 10 minutes.
So yeah, if a Rise and Scream is offered and you have a pass, it is DEFINITELY worth losing the sleep to attend!
-Julie