Updated place to fly in SF Bay Area/East Bay/South Bay

[MavicPeter]

That is from an FAA sectional chart, which one gets painfully familiar with as part of trying to pass a Part 107 test. You can download these for free here:

https://www.faa.gov/air_traffic/flight_info/aeronav/digital_products/vfr/

The yellow is urban areas, I believe. Not actually shown in the legend but that what it appears to be.

Yellow areas are indeed urban areas (or as the FAA states "populated places")
See page 35 of this guide from the FAA:

https://www.faa.gov/air_traffic/flight_info/aeronav/digital_products/aero_guide/media/editions/16Jul2020/cug-complete.pdf