I have a couple of servers that hang when I attempt to reboot them.
No to be clear the command I'm issuing is "shutdown -h -r now".
The server will start to go down but the shutdown process hangs for about 30minutes then finishes shutting down.

Troubleshooting so far:
-Reviewed /var/log/messages for errors during the shutdown,there were none. Was able to see the approximate time gap.
-Since the time gap in the log hung after a lvm-monitoring was stopped I renamed the "K" file that came after it (sysstat) so it would be skipped, bounces that server and shutdown again and it still hung.
-Tried disabling the NIC,umounting all NFS mounts, disabling/uninstalling vmware tools, disabling acpi option and still the issue persist. Did one change at a time.

The server continues to boot quickly and perform as expected otherwise, but I need to figure off this hanging on shutdown problem.

-h and -r are antithetical http://linux.die.net/man/8/shutdown; that may be part of the problem

I have used for a while now without any issues. Your correct about switch contradiction I was using.
With that being said; I used and it still hungs.

'reboot'?

The reboot command hangs as well.

It may just be a recap of what you have seen in /var/log but have you tried looking at the dmesg Kernel Ring Buffer? Perhaps try one of these restarts that take the time and record when you issue the (reboot / shutdown) comamnds. Then look for the events that occur from this point forward in the dmesg output onward and see if there is anything that explains this. I know that system management of the NIC can in some situations cause long booting but I am not sure if I have seen this when shutting the system down.............