WW, the height of cool jazz is usually from 1953 - 1960, though obviously people went on doing it after that. You probably got some post 1960 Miles. You should try some others in the earlier period, the seminal record being "The Birth of the Cool", which was recently reissued. Miles worked with Gil Evans on various classics like Sketches of Spain, etc. Anything of Bill Evans (the pianist on Kind of Blue) in that period ("Everybody Loves Bill Evans", etc.) is terrific (anything by Bill Evans anytime is terrific), early John Coltrane (Ballads), again pre-1960, 61.
yours, Peter T.