Some of the most heavy used DMR frequencies are part of trunked systems. Here are some good ones to monitor:
DMR Systems
Creative Communications Sales and Rentals Trunking System Profile
www.radioreference.com
Valley Metro Transit System DT3 Trunking System Profile
www.radioreference.com
Air Comm Trunking System Profile
www.radioreference.com
NXDN
Com-Rents (NXDN) Trunking System Profile
www.radioreference.com
Southwest Mobile Communications (NXDN) Trunking System Profile
www.radioreference.com
There are hundreds of other DMR and NXDN business radio frequencies in the valley. There are a few documented in the database, but most business frequencies have not yet been reported. Search 461-465mhz and you will likely find many.
This sit search DMR and NXDN FCC licenses:
Searchable radio frequency database to identify authorized Digital Mobile Radio, DMR, users by county and state.
digitalfrequencysearch.com