Maximizing usage on one drive only while the others are idle is unlikely to be optimal, watch the drive light, they are not there just for decoration. For a properly set up system the lights should look like Christmas in a disco. Linux offers software RAID but also support for some hardware base SCSI RAID controllers. Check what is available. As your system and experiences evolve you are likely to repartition and you might look on this document again.
Additions are always welcome.
There are a few more important things that are about to appear here. In particular I will add more example tables as I am about to set up two fairly large and general systems, one at work and one at home. These should give some general feeling on how a system can be set up for either of these two purposes. Examples of smooth running existing systems are also welcome. There is also a fair bit of work left to do on the various kinds of file systems and utilities.