I know that you specifically asked about towers, but I'll give you a rundown of the typical workday at Indy center.
First off, we work rotating schedules. Most controllers at ZID work either a 2-night, 3-day schedule, or a 2-night, 2-day, 1-mid schedule, or a 3-night, 2-day schedule.
I have a 2-3 schedule. I'm off on Mondays and Tuesdays, I then work a 3 pm to 11 pm shift on Wednesday, a 2 pm to 10 pm shift on Thursday, an 8 am to 4 pm shift on Friday, a 7 am to 3 pm shift on Saturday, and a 6 am to 2 pm shift on Sunday.
While at work we usually work for an hour and a half on position during each session, then we take a forty minute break before going back to the area and starting again. They try to get us a break before we hit two hours since the brain starts to get a little mushy and prone to mistakes after two hours of continuous intense concentration.
While on break, some controllers read in the break room, others watch TV
in the cafeteria, while others watch movies on portable DVD players, and some just walk around the center's grounds.