Limited hotel availability
Reservations at the official Microsoft Ignite conference hotels are based on a first-come, first-served basis to those participating in the in-person San Francisco experience. If you are unable to see a particular hotel on the Hotel page of your registration, this means that that particular hotel room block has reached capacity, and you must book a reservation at one of the hotels that are currently listed as available.
If some of the days are blocked out, this means the hotel has no more available rooms that evening. The Microsoft Ignite event website shows a complete list of the hotels set aside for the event, while the Registration website only shows which hotels are currently available.