I agree about the partitioning. The habit of splitting things into various partitions came from large multi-user systems where it has definite advantages. But for workstations, or other essentially single user systems it is definitely sub-optimal. Your experience is the exact problem - no space in one partition and space available in another but not usable. My advice is one partition per disk unless your hardware requires a /boot partition to guarantee the bootable images are at low disk addresses.
One of the advantages of having separate partitions is that a runaway process that (say) generates a huge file in /tmp or /home and fills up the filesystem will not fill up the root filesystem if that is one a separate partition. Filling up the root filesystem is certainly something to be avoided if possible.
Using LVM gives most of the needed flexibility for partition resizing without losing the "safety" of the separate partitions.
Paul.
