I keep it fairly simple. Just one ext4 partition, for / per distro with the bootloader
installed to the partition. The system came with Vista and a recovery partition on a 500GB
hard drive. Here's the process I followed:
1. Shrink the Vista partition (I gave it 50 GB)
2. Create a 1GB boot partition immediately following the boot partition.
3. Create an extended partition for my Linux distros and misc. files
4. Create a 20GB partition for Fedora, and a couple of 80GB partitions for the misc.
stuff
5. Install Fedora using the 1GB boot partition as /boot, and the 20GB partition as / (no
swap). Install grub to the hard drive's MBR.
6. Unmount /boot and remount the boot partition on /media
7. Copy the contents of /mnt to /boot
8. Install grub on the Fedora partition
9. Manually modify the grub config file on /media to chainload the bootloader on the
Fedora partition.
Keeping a separate boot partition not tied to any one distro I might happen to install
works for me; YMMV.