The first question is not “what music?”
Before choosing genres or artists, define the intention: what should the environment help people feel and do? Conversing with ease, celebrating, waiting, working, having a brief meal or staying longer are different contexts.
Volume is an operational decision
The same setting can work at one time and lose coherence when the dining room fills, the team changes or other sound sources accumulate. Volume should not be treated as a fixed preference of whoever is in charge that shift.
Simple criteria for routine
Define responsibilities; record scenes for operational moments; establish when volume is reviewed; and create a channel for the team to report discomfort and deviations. This does not eliminate the need for technical evaluation where an acoustic issue exists, but it reduces recurring improvisation.
Music is part of a larger layer
Reverberation, equipment noise, conversation, architecture and patterns of use remain. Well-chosen music does not alone correct an unbalanced sound layer; it must work with the environment’s other decisions.