Depending on your antenna setup and local geography, you may be able to hear more than one site. I would suggest programming the two or three sites nearest you. Traffic is not the same on every site, especially on large statewide systems, so you may miss stuff of interest if you only program one site. Programming more than one site also gives you a backup option if a site fails.
If you click on the site link (not the town/county link next to it) you can see a map with the tower location(s) for the site.