I was chosen for a 4-day civil trial downtown once, and it was actually kind of fun.
I would want to do it again for a civil trial, but around here the courthouse for criminal trials is very scary. I live in the same county as the city of Chicago, so we are assigned to the same criminal courthouse as big gang-related trials and other high-profile cases.
I have had friends and coworkers that have served jury duty at that courthouse and they all say that they had to park in the same parking lot as family and friends of the defendant/plaintiffs. They have all said they have been scared they would be followed. My boss actually just told me yesterday that she was called for jury duty there once on a day a high-profile judgement was supposed to he handed down, and all of the people in her jury pool were escorted into a secure hallway with no windows and locked doors while police stood guard with rifles. The potential jurors (that weren't even involved in that case!) were told to stand against the walls of the hallways and not to talk until the building was cleared of all families/friends of the person on trial. They stood there for about 30 minutes, she said.
Not a juror, but in the same courthouse - a few years ago, a resident of my very safe and nothing-really-happens-here town was a witness (he was a security guard at the place and time of the incident) to a crime committed by some gang members. He spent the morning testifying at the same criminal court, then drove home and pulled up in front of his house in time to see his wife and 18 month old son for lunch. A car had followed him from the courthouse, pulled up next to him and shot him point blank in the head and chest. He died in his car in front of his house. His wife heard the gunshots and ran out to find her husband dead. It took almost a year for our police to find the murderers, but they eventually did. They were allies/friends/fellow gang members with the defendant, and had followed the security guard back to his house from the courthouse parking lot.
They have a long way to go in terms of security at that place.