Well coinbase finally did add my girlfriend as an authorized user and I was able to w/d.  Trying to think of some nice thing I can say about the experience....

OK, it doesn't seem like their motivation was to nickel-and-dime me (aside from their standard exchange margins), and it doesn't seem like the problem was that they are out of money.

On the other hand, I can't say I'd recommend Coinbase to anyone or that I'm likely to continue with them myself.  That experience definitely left a bad taste in my mouth.