No separate partition - but ...
 

I went with Mepis' default /=10G, /swap=1G , and the rest to /home (200G++).
Apache, and apt cache get stored somewhere in /home because I changed the default directories to symbolic links elsewhere with abundant space.
It is especially useful in that if I need to reinstall the os, I can reinstall all packages without bogging anybodies bandwidth (and it's faster).
Since reinstalling wipes out / I backup various /etc , /opt/ and /var files that aren't linked to /home/* . It's workable enough, however movies and music have swamped the hd capacity - guess what I need for xmas.

On my home machines I have a reasonably large (4GB) root partition that includes the /var directory. However on the servers at work I create adequately sized directories for everything and minimise the root filesystem. I can't remember what size I created them as... I imagine at least 2GB since there is an over abundance of space (the machines have multiple disks for database performance, left over space was the result).

hmm. I'm talking a bunch of servers. / set up with 10G partition. no separate /var. However, I have log rotation set up, I have a monitor script that watches partition usage and notifies me if any partition exceeds 90%, all my software installs go into /usr/local (I'm on Solaris), and I have a separate /archive partition where I keep historical stuff if I want it (just for example, I keep mail logs for at least a year, with 2 million lines a day in the mail logs).

Part of my rationale is that disks have gotten bigger, Sun's traditional install with a bunch of things broken off into different partitions uses up too many of the available partitions in my opinion (leaving a large amount of space with too few remaining choices to break it up if I want to), and I don't see the point in forcing the space balancing decisions at install time. If one area swells up and another doesn't, I would hit the wall sooner if they are each defined at install. But if I let them all share 10G, then I don't hit a wall. It's more flexible. And, if I define /var and it fills completely, it's going to cause trouble anyway.

so, ...

Solaris, nice!

The servers I was talking about with separate /var partitions are also Solaris (Sun Fire T2000). Our older servers that I replaced had one big root file system, and when it filled up the kernel would panic... very bad! You can put stuff in root, but be sure you monitor it very closely. Given that you can have 6 partitions on each mirrored pair in a Solaris box, and I had 4 disks, allocation /usr, /opt, /var, swap, /export/home, /u01, /u02, and a couple of raw filesystems for sybase was not an issue. The only concern was balancing disk queue lengths between the mirrored pairs (ie database partitions versus archive log partitions).

Anyway, with careful planning and analysis of the old servers, I have some very nice machines that run seamlessly, and the usage of root never varies.