I am in favor of chokepoints. I'd say the distribution should be 1 Fertile Province for every 5 provinces or so.

Also since this is a large map and more than likely going to be used for 17 Nations. You can divide everything by 17 to find a balance of barren, forest, mountain, river, and farmland provinces. I did notice the prevelence of barren land, but maybe it's just because there is not alot of green. Perhaps you could make or IW has a 'waving wheat field' icon you could put in a few provinces.

And yes, it looks terrific. Maybe you could even place a tower icon on the edge of a chokepoint so it's more visual.