The University of Auckland's city campus is in the central city area, adjacent to Albert Park. There are numerous hotels and backpackers within walking distance of the campus, which you might choose from.
We offer the following as a guide only, and an indication of range.
These options are all especially close to the symposium venue, and conveniently situated near amenities. 
Hotel Pullman (5 star) http://www.pullmanhotels.com/gb/hotel-8219-pullman-auckland/index.shtml 
The Quadrant Hotel (4 stars) (recommended) http://www.thequadrant.com/
Quest on Mount St (4.5 stars) (offers suites with kitchens if you prefer to self-cater)http://www.questapartments.co.nz/Accommodation/138/new_zealand/auckland_cbd/quest_on_mount/welcome.aspx
Empire Backpacker Hostel (cheap, new and practically on campus. Offers self-contained units and private rooms with shared facilities)  http://www.aucklandbackpackers.co.nz/.