[Scott Hebert]

For me, all things being equal, I prefer to do a spiral. Things are rarely equal.

In general, I would attack the single richest province adjacent to my army that I thought I could take. The flip side of this would be attacking the weakest province.

I remember a discussion a while ago by Gandalf and a few others about this. Some do well with circles, some with lines, while Caelum can do something of a 'dipping toe' method of expansion.

For me, though, once I have an 'indy crushing' army, I take a spiral.