To standardize the definitions, being doable means when you look at a girl you decide you would have a one night stand with her, and being datable means when you look at a girl you decide she could be girlfriend material (assuming she has a good personality).
dpeneds what you're looking for. relationships or hookups?
If she's dateable, that means she's doable by default. A girl being dateable - much better looking. Doable = attractive enough to bang, but not attractive enough to date. Let's not kid ourselves that our dating value has to do with anything but looks in the first three months or so.