This is going to be somewhat informal, as I know that people are going to want to be in various sessions or perhaps arriving later.
But based on the convention schedule, I think the best time to meet would be between 11:30 and 12:30 on Saturday.
As you walk into the hotel on the Balbo St. side, west of Michigan Ave., there is a car turnaround leading to their garage. If you walk straight ahead from there, at the northeast corner of the building, there is a bar with a fair amount of seating. It's never very crowded in there, so there should be space for BCB'ers to hang out for a while. I'll be wearing my BCB t-shirt.
I've also posted a diary that you can use, if you are NOT coming to the convention, for posting questions that you might like those of us who are going, to pose to Dusty Baker or Jim Hendry in their Saturday morning session.