I had similar issues to you. I found the script "rescan-scsi-bus.sh" which you can find on google works wonders for RHEL5.x within VMWare.
I tend to only use the rescan commands you put above on physical servers running RHEL5.x. I have not tried the differences between RHEL5 and RHEL6 though.
If that doesn't help you can reset the FC port (enable/disable) on fibre switch.
Of course, that requires you to check all the hosts on that port if they have multipath configured properly, or you will lose access to those disks until port is up.
This script only detects the extra space on the fdisk. The problem in this case is that I am trying to extend a current FS. So when I add in the extra partition using fdisk I am unable to pvcreate the new partition as the resource is busy.
Anyway, the solution is to use partprobe against the device after the new partition has been created in fdisk. Only is it then possible to pvcreate the dev.