A link to a great article discussing grid size and why 1 meter is better than 5' for your grid. Unfortunately he doesn't point out the virtue of the hex, but it is a D&D site so I won't harp on that.

http://forums.gleemax.com/showthread...6#post16079896

Interestingly enough two of my favorite systems Hero and GURPS both use meters - Hero uses 2/hex and GURPS 1/hex - and I've always felt that the spacing just "felt right" on maps. Now I know why.