gee, Ian sounds like either your soil or climate is distinctly adverse to banksias---which is odd because you have had success with so many other s.h. plants. integrifolia and marginata (which tends to have smaller leaves than integrifolia) are reasonable shots for mild areas of the pnw because they are generally good resprouters if damaged by frost or fire. i think that jim g. in yaachats had a fairly large integrifolia. i had canei but it seemed very finicky and died after a few years---the related species integrifolia, marginata, and saxicola seem easy as long as drainage is very good and soil fertility is very low. telopea, grevillea, lomatia, and hakea seem to be easier to please.