Dear reader, I love Banksias and have been jotting a few notes on those in my region and around Sydney. Hopefully it may inspire Sydneysiders interested in filling a few spots in their yards with flora local to the region or even suburb.

Cooks River Area

I live in Dulwich Hill in the Inner West. The nearest remnant of bushland to my house is Nannygoat Hill, a great place for seeing local flora. Now I noticed 3 species of Banksia there: good ol' B. serrata, 2 forms of B. integrifolia trees (one with even broader, obovate leaves, and the other with normal leaves) and 2 (or 3) forms of B. spinulosa spinulosa shrubs. On top of the hill were some shrubby, almost bonsai or Birthday Candles-like black styled plants, while lower down the hill were some taller, maroon styled plants. Also, next to a nearby playground were couple of young plants with gold styles in a revegetation area (maybe they weren't local stock, I don't know).
B. oblongifolia grows on sandstone ridges, and can be found in Girrahween Park in Earlwood - I saw some dingy looking plants there. B. aemula also allegedly local to the region (the latter in the eastern parts around Alexandria I think)
Problem is, most nurseries only stock B. spinulosa collina instead of the local spinulosa, which occurs north of the Hawkesbury River - a nice plant but not strictly local.

Sydney's East

I also visited the Banksia scrub down in Little Bay, with a marvellous boardwalk through it. Here were lots of B. ericifolia ericifolia, both orange-flowered and red-flowered plants side by side, as well as B. aemula. Allegedly, the latter plant is supposed to be more tolerant of indifferent drainage than its bigger relative.
The variable B. marginata is also a local plant of both Waverley Council area and Sydney's south. Speaking of the south, B. paludosa paludosa is a local plant of the Woranora Plateau.

Banksias in Street Planting

I've seen B.serrata and B. integrifolia used alternately down Clovelly Road in Clovelly toward the water (this was a clever place as the road runs along the top of a ridge and so would have good drainage, important especially for B. serrata.). Also, B. ericifolia is scattered about the streets in Bexley north and doing OK, again on streets located on top of ridges.