Aside from CLI show commands, you may want to look into 3rd party software with traffic visibility. I cannot give specific names as applications and vendor recommendations are off-topic.
However, there are a lot of options out there that give granular visibility of the traffic flows and break them down and track traffic tags such as IP ToS. Look for applications with NetFlow support.
Cisco basic NetFlow v5 will track the following information:
- Ingress interface (SNMP ifIndex)
- Source IP address
- Destination IP address
- IP protocol Source port for UDP or TCP, 0 for other protocols
- Destination port for UDP or TCP, type and code for ICMP, or 0 for
- IP Type of Service
While you may not be able to tell whether queues are explicitly being congested from the reports, you are often able to tell whether tags are being properly applied and honored.