My first hackintosh installation was a JaS 10.4.7 DVD on a multi-booting laptop with a single hard drive.

Alas, times have changed!

These days, we have almost unlimited options. Retail seems to be the wave of the future for hacks...

But how do you make such choices and which choices are based on ease of use, ease of management, or based on sound advice?

A vast majority of people who develop for our community began utilizing various options that appeal to me:

1) Use a separate hard drive for OSX only

2) Multiple partitions per hard drive for OSX

3) Use a separate hard drive for DATA only

4) Choosing a better format/partition scheme suitable for a more authentic hack
VS
Choosing a format/partition scheme suitable for cross platform use/editing/etc.

I'm curious about the concept of creating the most safe environment for production AND testing.
Most importantly, a solution that isolated OSX goodness from any other OS and DATA.

Having multiple hard drives etc which plan would make the most sense for my future hackintosh?

I'm interested in your solution, the setup you're using now, and any thoughts/possible pitfalls people ought to be aware of.

I prefer to use 2 Partitions with Multiple OSs installed. In my case, XP and OS X.
For data I use either DVD/CDs or just a memory stick, but mostly I am lazy and dump it on the HDD!

The Chameleon v2 Boot loader makes it very easy for multiple partitions and disks.

The most important points are to partition the drive as GPT and to allocate the first three partitions (numbered 2-4, because 0 is EFI) wisely. The way I propose below allows you to use DIsk Utility to create and boot to any number of HFS+ partitions with various Mac OS X installs.
Being extremely lazy, I follow these considerations. Note that for n00bs, this is also the best approach in my humble opinion as it leverages Disk Utility to do the heavy lifting of keeping the GPT and MBR partition tables in sync.
1. Always have one of the first three partitions in either FAT or NTFS format. This ensures that Disk Utility will keep the MBR partition table in sync with the first four GPT partitions (EFI + partition numbers 2-4), saving you a LOT of trouble down the road.
2. Format one of the first three partitions in HFS+ to use as pre-boot partition with Chameleon and its Extra folder
3. Plan ahead for flexibility before you install OS X as moving its partition around later is a pain.

My current main 1TB drive is laid out as follows:
1. EFI partition (I would not re-format it as HFS+. If a boot loader wants to be on my EFI partition, it is more than welcome to by my guest, but it needs to be able to install on the original EFI FAT32 partition, period)
2. Main Mac OS X partition (640GB)
3. Windows Vista partition (80GB)
4. Chameleon pre-boot partition (0.5GB)
5., 6., 7. various Mac OS X/Server partitions for testing new releases.
This gives me the following flexibility.
- I can do with partitions 5, 6, ... whatever I like and do it from Disk Utility
- If I want to get rid of Vista (who doesn't), I can just delete its partition in Disk Utility and resize the Mac OS X partition live (i.e. while having OS X running from it) to fill up the gap.

An alternative scheme providing even more options would be the following:
1. EFI partition
2. Chameleon pre-boot partition (4GB)
3. Main Mac OS X partition (640GB)
4. Windows Vista partition (80GB)
5., 6., 7. various Mac OS X/Server partitions for testing new releases.
The advantage of this is that if you feel adventurous down the road, you could split the Chameleon partition to obtain a Windows boot partition, which could then be used to boot a number of Windows installs from this drive. This likely will require you to modify the MBR partition table to have primary partition 4 as an extended partition by hand, or maybe gptsync could do this for you.
However, I'm too lazy to go this route, therefore I went for the fastest option, having Mac OS X at the very beginning of the drive. If I ever buy a Mac Pro, I could also easily re-use this drive in it by just erasing all the junk partitions and re-size the main Mac OS X partition.