Annnnnnd... one more thing:
In the choosing of starting locations, there was a subtle strategy involved. I debated discussing this, because it says quite a bit about strategy, and I'd prefer to NOT taint y'all's plans with my DM's View of things. However, it's come up in a couple of emails, and I'd rather share it with everyone than with just the few people who brought it up.
When designing the arena, I decided on a number of variables that would matter the most, primarily:
Distance from other points in the arena
Line of sight from other points in the arena (and concealment)
Barriers to movement
Natural visual sinks (just from an art theory perspective)
For distance, the four corners offered the longest overall distance from other points in the arena, making them ideal for archers and spell casters. This was a simple enough issue - I rounded the arena slightly so that I wouldn't end up with people crowding the few squares of the corners themselves (while amusing to think about, I wanted some breathing space for everyone).
At the same time, the real melee types would tend to pick locations closer to the middle, where they would be most likely able to close quickly with whoever they chose to target.
For line of sight, the hills and the lake break things up for targetting purposes. That makes the top of the upper left hill (I call it Fort Hill) the MOST ideal for anyone who wants flexibility between hiding and laying long-range smack.
The middle-sized hill (I call it Cautious Hill) does not provide as great an advantage to long range attackers, but it provides the only real barrier to line of sight
from Fort Hill. That makes it look like a good place to hide for a round or two.
For barriers, I divided the arena into two with the river. It's not a perfect barrier, just a mild one, but it creates two major visual spaces in the arena - the northeastern area looks terribly vulnerable and open, and the southwestern area looks more broken up and protective. Again, this enhanced Cautious Hill's appeal to that group, and helped push everyone away from the northeastern corner.
I also made the lake as a bigger barrier to movement, and gave it only a few squares along the edges. I wanted that area to look like a trap, to push most people away from the southeastern corner.
For natural visual sinks, I laid it out to draw the eye inexorably along the left side of the arena. I didn't really intend for there to be any fighting in the east half of the arena - the whole purpose of that area was to provide the visual oomph to push the eye to the west.
My ultimate goal was to have three groups: one in the center, between Fort Hill and Cautious Hill, one physically
on Fort Hill, and one in the southwestern corner, preferably clustered a bit close to Cautious Hill.
The central group would primarily be those folks who were looking to lay smack and weren't too picky about who. I expected Cholestus and Master+Blaster to be here, and possibly one or two others, and I was rather wrong

.
The Fort Hill group would be the strongest contenders, the ones who were ready for a fight right out of the gate, but who wanted some tactical options for line of sight, distance, and who they could target.
The Cautious Hill group would be the cautious ones who wanted some time to prep, little knowing that Hethas planned to have them all crowded together right off the bat (Rillos and Izad stumped me by taking a chance on the even more crowded looking southeastern corner).
The larger strategy, of course, would be to see this, figure out where people are likely to end up, and go for a spot that suited your needs based on where everyone else was going to be. If I had a build that was made for Fort Hill, for example, I'd take Cautious Hill. Fewer options, but I'd be closest to all the people who'd built around having extra prep time.
If I had a Cautious build, I'd stuff myself into a corner, preferably the northeastern corner. Or I'd do what Rillos and Izad did.
And if I was a Central gimme-a-fight type, I'd pick Fort Hill, where the biggest, meanest, juiciest targets were. Of course, that wouldn't result in a quick win, but I'd probably go out in a blaze of glory

.