Lancopa,
If you want to hear EVERTHING in the county, you'll need to program the simulcast also. Here's what I have found in the past years: If you just want to listen to fire and ems, program in a non-simulcast tower. The TMI tower will broadcast ems and fire from anywhere in the county. Non-simulcast towers, like TMI, will not broadcast PD that use simulcast. You need to program in the simulcast to hear absolutely everything possible. The only downside to that is simulcast is hard to listen to because of multipath. In fact, I had to build a yagi to point at the closest simulcast tower to get the best reception. I plan on making a video this afternoon to show my progress with decoding the system. I'll post a link once I do it!
Good luck!
P.S. If you travel near TMI, you should be able to receive from the simulcast on Chambers Hill.