Originally posted by Skyline
Easy - 3 Root partitions and a Swap partition (as your 4th)
the only disadvantage to that is if you finally decided to go with only one distro, you would have to copy your /home data from each one to somewhere temporary while you set everything up again, then copy it to the new place, etc. whereas if you have a dedicated /home partition, you could even wipe all three distros clean and start over with a single one, or a different one, or whatever you wanted to do, while maintaining your data with minimal hassle. just something to consider.