Just in case you have been told, as a couple of people have already reported, that there are no rooms available at the conference hotel for the sprint days, please don't give up! This appears to be a glitch in the hotel's reservation system.
To the best of my knowledge the agreement with the hotel is that rooms will be bookable at the conference rate even after the PyCon guaranteed allocation is used up, and indeed as long as rooms continue to be available. So persist, and if necessary call 1-800-228-9290 to demand the room rates that PyCon delegates are entitled to.
Thanks to David Goodger for the appropriate extract from the contract. I wonder if Marriott need some help with their information systems? I bet they aren't written in Python!