Maybe the difficulty setting has something to do with it. At the lower intelligence settings thay may just be too dumb to recognize a good thing. I see the tiles used correctly a lot of the time, and sometimes not as much. The Yor sure don't seem too bright, in any case. I have them set at genius right now, and they still can't figure out to build a few farms and not place embassies on 300% research tiles. Maybe if they had the extra people and research, they could better fend off my troops and ships when they declare war on me.