When I started reading grown-up SF decades ago it was with Bear, Bova, Niven, Pournelle, and the like. Back then Eon, Blood Music, and Ringworld (for example) were mind-blowingly vast concepts.

As an aside (and purely because it's probably my turn for some hefty downvotes) I'd definitely agree with the comment elsewhere in this thread about the Foundation books being overrated. Almost unreadably dull and feeling more like any concept of 'plot' is just a carrier for a couple of mediocre ideas.