I think it's personal preference. We're deciding on recessed lights too and were putting 5 in the kitchen more spaced apart. Basically our kitchen is an L shape with a rectangle island so the island has 3 hanging pendant lights which are pretty bright. Well do one recessed light near the pantry...one in the corner and then another by the counter next to stove. The other two are in an area in between the island and dining set...but 3 are in line and two are in line. So they are in a pattern.

In our living room were only doing two recessed lights near the tv. The other walls have sconces. And a light hanging in the middle on a dimmer.

So for me I like patterns and to be spaced equally rather than scattered.

There is more information here

http://ths.gardenweb.com/forums/load/lighting/msg010127153310.html

there is a follow on thread to that as the limit of 150 messages on the original has been reached.