Tridion Montoring is available for 2011. There is a monitoing endpoint which you can hit to ensure that Tridion is Healthy or you can setup as a service.
You have to setup and install monitoring agent before you can do this. Refer this section and install per you needs
Tridion Monitoring Documentation
Alternatively, you can also monitor individual Tridion services using tools like SCOM for Windows and have alerting setup on the same to take action.
As far as logs are concerned use tools like Splunk to filter out information that you are looking for in the logs as it provides easy search capabilities so that you don't have to parse huge logs by your self and you can also plot graphics of common errors as well.
Well, you will have to use a combination because even if you monitor services for failure, you will have to figure out the root cause for failure using logs so that you can fix the issue. You can use SCOM monitoring for Tridion Services and NLB health check for deployer, oData services (if you plan to use them) which will cover the monitoring needs.