Hi,
A few things that you can check are:
1. Cisco Unified Reporting - to get details about cluster database , replication , mismatched loads on phones etc
2. Outout of following commands on each server to check for core dumps , ntp/dns/tomcat issues , disk/ram/cpu usage etc
show status
utils core active list
utils diagnose test
3. utils disaster_recovery history backup - to check for any issues with backups
4. You can use RTMT as well for live monitoring of these servers.
HTH
Manish