For Waterbury, just program in all the system frequencies in conventional mode without any delay. The system has a lot of mundane users on it during the day, but at night all you'll hear is PD and FD. There are also some conventional frequencies in the 853 MHz. range (used to be 868 pre-rebanding) that are used for mobiles and portables to talk direct to one another that get interesting. 853.9875 MHz. was the most popular. I'd also put in all the mobile system frequencies so you can tell when there's nearby activity.
Both Campion and AMR run ambulances in Waterbury. You'll want to monitor them as well, usually with a separate receiver because they are always busy. Unfortunately a lot of the more interesting business/industrial users have switched to MotoTRBO, so you'll won't be able to hear them. Most of the local PDs up and down the valley are still analog or unencrypted P25, so there's no problem there.