The waits out of Terminal A usually aren't bad, but I would show up about an hour ahead of time for a 7:30 flight just in case. There have been some weeks where lines are almost hour long, and I can never reliably predict when they will occur (outside of the standard Thanksgiving, Christmas, Spring Break time frames). I would say a Silver's chance at an upgrade is about 60-70%. I usually made the upgrade back when I was Silver.