My plan (for now) is to handle any bitcoin transaction as a EUR transaction, exchanging the funds instantly. So you can't be guaranteed to be refunded in bitcoin, but may have to accept a refund in fiat currency in case of a refund. We have to pay the hotel provider right away, in Euro, so holding on to bitcoin, would be a bit of a risk for us, do to it's volatility.

Also about half of hotel bookings are made at non refundable hotels, so for those, this would not be a problem.