In terms of what "cool" generally means, I don't think Pink Floyd were as "cool" to the street as bands like The Animals were in their heyday - the Floyd were at first only supported by a tiny Uni-based group and then when they suddenly went huge were too big to be "cool" any more. Similarly, the Beatles were never exactly "cool" because they were too mass-market. Pink Floyd were cooler before everyone knew about them. They might be getting a little cooler again now in old age judging from recent programmes, as are people like Mick Jagger/Keith Richards.
I would go for those who were a little less than stormingly mega-huge but who had an incredibly cool, sexy or powerful image, like the Doors and Jim Morrison. Later on, people like Hendrix were cool, despite being big, because the mass-market was opposed to them. In the 70s, it was bands like the New York Dolls. Some bands keep become more and more cool in hindsight - King Crimson for example. Some groups were hated by the Cool at the time only to eventually be admired by them - Abba? Some people regarded as hyper-cool from that era, like David Bowie and Bob Dylan, have become much less cool as they left the path of Coolness and descended into self-satire and graceless self-admiration.
In the 80s, 90s and 00s it gets harder because a lot of bands knew how to be cool, so they rehearsed coolness professionally and the sort of accidental genius recognised as Cool by an early, perceptive minority (like us) gets sidelined. However, people like Radiohead, Pearl Jam, even mass-market entities like U2 and (particularly) REM - even though U2 has now become anything but cool, they were once, in some long-forgotten time, before everyone just wanted to stop looking at Bono, in the interests of his own mental health.
Coolness has now become so fragmented a concept that it is hard to point the finger and say who is cool.
Throughout musical history since the war, premature death has been the high road to uber-coolness. Hendrix, Joplin, Bolan, Morrison, Curbain - the list goes on.