Call the Hilton Madison Monona Terrace at 877-510-7465 or book online to book a room for the group rate of $139 per night. The group code is "PROTO".
This block expires September 30, 2020.
I've put together this list from Booking.com as of June 27, 2019 (listed from closeness to the convention):
|Hotel||Rooms Left||Average Price Per Night||Distance|
|Hotel Indigo||1||$200||Long Walk|
|Holiday Inn Express||3||$175||Drive/Taxi|
|Americas Best Value Inn Mayflower||10+||$85||Drive/Taxi|
|Spring Hill Suites||5||$225||Drive/Taxi|
Plus there are many more you can find on Booking.com. Or you can rent a house/apartment on AirBnb.