No matter what, Shipping by Weight isn't an option

I have tried everything I can think of but no matter what I try, Ship by Weight is never an option at checkout.

OC 1.5.4.1

1. Check your weight classes, that your default has the value 1.000 and others have the appropriate conversion value.

2. Check your product weight classes, and make sure they're set correctly.

3. Make sure your rates in Weight Based Shipping are entered using your default weight class.

4. Check your geo zones, and make sure they are associated with the correct locations.

The Geo Zones turned out to be my problem.

(can't wait for the docs to actually be useful!)