Pro tips

Standing tables/counters: no
Friendly staff: yes

+ Tons of space
+ Private study rooms if you get a library card (of the resident variety)
+ Huge domed study room on the 8th floor
+ Views of the city
+ Silent archives and rare books room on the 9th floor, as well as a small art exhibit space.
+ Printing
+ Tours

- opens late and closes early
- lower floors can be noisy, see http://www.voiceofsandiego.org/central-library/why-i-probably-wont-be-back-to-the-new-central-library/